Change distributor latency to have a regular expression equals (#11827)

Currently, the distributor latency panel uses a "=" in the code as
opposed to a "=~", causing the panel to render as empty. This is to fix
that issue.

**What this PR does / why we need it**:

**Which issue(s) this PR fixes**:
Fixes #<issue number>

**Special notes for your reviewer**:

**Checklist**
- [ ] Reviewed the
[`CONTRIBUTING.md`](https://github.com/grafana/loki/blob/main/CONTRIBUTING.md)
guide (**required**)
- [ ] Documentation added
- [ ] Tests updated
- [ ] `CHANGELOG.md` updated
- [ ] If the change is worth mentioning in the release notes, add
`add-to-release-notes` label
- [ ] Changes that require user attention or interaction to upgrade are
documented in `docs/sources/setup/upgrade/_index.md`
- [ ] For Helm chart changes bump the Helm chart version in
`production/helm/loki/Chart.yaml` and update
`production/helm/loki/CHANGELOG.md` and
`production/helm/loki/README.md`. [Example
PR](d10549e3ec)
- [ ] If the change is deprecating or removing a configuration option,
update the `deprecated-config.yaml` and `deleted-config.yaml` files
respectively in the `tools/deprecated-config-checker` directory.
[Example
PR](0d4416a4b0)

production/loki-mixin-compiled-ssd/dashboards/loki-writes.json

@@ -142,7 +142,7 @@
                   "steppedLine": false,
                   "targets": [
                      {
-                        "expr": "histogram_quantile(0.99, sum by (le) (cluster_job_route:loki_request_duration_seconds_bucket:sum_rate{cluster=~\"$cluster\", job=~\"($namespace)/(loki|enterprise-logs)-write\", route=\"api_prom_push|loki_api_v1_push|/httpgrpc.HTTP/Handle\"})) * 1e3",
+                        "expr": "histogram_quantile(0.99, sum by (le) (cluster_job_route:loki_request_duration_seconds_bucket:sum_rate{cluster=~\"$cluster\", job=~\"($namespace)/(loki|enterprise-logs)-write\", route=~\"api_prom_push|loki_api_v1_push|/httpgrpc.HTTP/Handle\"})) * 1e3",
                         "format": "time_series",
                         "intervalFactor": 2,
                         "legendFormat": "99th Percentile",
@@ -150,7 +150,7 @@
                         "step": 10
                      },
                      {
-                        "expr": "histogram_quantile(0.50, sum by (le) (cluster_job_route:loki_request_duration_seconds_bucket:sum_rate{cluster=~\"$cluster\", job=~\"($namespace)/(loki|enterprise-logs)-write\", route=\"api_prom_push|loki_api_v1_push|/httpgrpc.HTTP/Handle\"})) * 1e3",
+                        "expr": "histogram_quantile(0.50, sum by (le) (cluster_job_route:loki_request_duration_seconds_bucket:sum_rate{cluster=~\"$cluster\", job=~\"($namespace)/(loki|enterprise-logs)-write\", route=~\"api_prom_push|loki_api_v1_push|/httpgrpc.HTTP/Handle\"})) * 1e3",
                         "format": "time_series",
                         "intervalFactor": 2,
                         "legendFormat": "50th Percentile",
@@ -158,7 +158,7 @@
                         "step": 10
                      },
                      {
-                        "expr": "1e3 * sum(cluster_job_route:loki_request_duration_seconds_sum:sum_rate{cluster=~\"$cluster\", job=~\"($namespace)/(loki|enterprise-logs)-write\", route=\"api_prom_push|loki_api_v1_push|/httpgrpc.HTTP/Handle\"}) / sum(cluster_job_route:loki_request_duration_seconds_count:sum_rate{cluster=~\"$cluster\", job=~\"($namespace)/(loki|enterprise-logs)-write\", route=\"api_prom_push|loki_api_v1_push|/httpgrpc.HTTP/Handle\"})",
+                        "expr": "1e3 * sum(cluster_job_route:loki_request_duration_seconds_sum:sum_rate{cluster=~\"$cluster\", job=~\"($namespace)/(loki|enterprise-logs)-write\", route=~\"api_prom_push|loki_api_v1_push|/httpgrpc.HTTP/Handle\"}) / sum(cluster_job_route:loki_request_duration_seconds_count:sum_rate{cluster=~\"$cluster\", job=~\"($namespace)/(loki|enterprise-logs)-write\", route=~\"api_prom_push|loki_api_v1_push|/httpgrpc.HTTP/Handle\"})",
                         "format": "time_series",
                         "intervalFactor": 2,
                         "legendFormat": "Average",

production/loki-mixin-compiled/dashboards/loki-writes.json

@@ -142,7 +142,7 @@
                   "steppedLine": false,
                   "targets": [
                      {
-                        "expr": "histogram_quantile(0.99, sum by (le) (cluster_job_route:loki_request_duration_seconds_bucket:sum_rate{cluster=~\"$cluster\", job=~\"($namespace)/distributor\", route=\"api_prom_push|loki_api_v1_push|/httpgrpc.HTTP/Handle\"})) * 1e3",
+                        "expr": "histogram_quantile(0.99, sum by (le) (cluster_job_route:loki_request_duration_seconds_bucket:sum_rate{cluster=~\"$cluster\", job=~\"($namespace)/distributor\", route=~\"api_prom_push|loki_api_v1_push|/httpgrpc.HTTP/Handle\"})) * 1e3",
                         "format": "time_series",
                         "intervalFactor": 2,
                         "legendFormat": "99th Percentile",
@@ -150,7 +150,7 @@
                         "step": 10
                      },
                      {
-                        "expr": "histogram_quantile(0.50, sum by (le) (cluster_job_route:loki_request_duration_seconds_bucket:sum_rate{cluster=~\"$cluster\", job=~\"($namespace)/distributor\", route=\"api_prom_push|loki_api_v1_push|/httpgrpc.HTTP/Handle\"})) * 1e3",
+                        "expr": "histogram_quantile(0.50, sum by (le) (cluster_job_route:loki_request_duration_seconds_bucket:sum_rate{cluster=~\"$cluster\", job=~\"($namespace)/distributor\", route=~\"api_prom_push|loki_api_v1_push|/httpgrpc.HTTP/Handle\"})) * 1e3",
                         "format": "time_series",
                         "intervalFactor": 2,
                         "legendFormat": "50th Percentile",
@@ -158,7 +158,7 @@
                         "step": 10
                      },
                      {
-                        "expr": "1e3 * sum(cluster_job_route:loki_request_duration_seconds_sum:sum_rate{cluster=~\"$cluster\", job=~\"($namespace)/distributor\", route=\"api_prom_push|loki_api_v1_push|/httpgrpc.HTTP/Handle\"}) / sum(cluster_job_route:loki_request_duration_seconds_count:sum_rate{cluster=~\"$cluster\", job=~\"($namespace)/distributor\", route=\"api_prom_push|loki_api_v1_push|/httpgrpc.HTTP/Handle\"})",
+                        "expr": "1e3 * sum(cluster_job_route:loki_request_duration_seconds_sum:sum_rate{cluster=~\"$cluster\", job=~\"($namespace)/distributor\", route=~\"api_prom_push|loki_api_v1_push|/httpgrpc.HTTP/Handle\"}) / sum(cluster_job_route:loki_request_duration_seconds_count:sum_rate{cluster=~\"$cluster\", job=~\"($namespace)/distributor\", route=~\"api_prom_push|loki_api_v1_push|/httpgrpc.HTTP/Handle\"})",
                         "format": "time_series",
                         "intervalFactor": 2,
                         "legendFormat": "Average",

production/loki-mixin/dashboards/loki-writes.libsonnet

@@ -65,7 +65,7 @@ local utils = import 'mixin-utils/utils.libsonnet';
                             $.panel('Latency') +
                             utils.latencyRecordingRulePanel(
                               'loki_request_duration_seconds',
-                              dashboards['loki-writes.json'].clusterMatchers + dashboards['loki-writes.json'].matchers.distributor + [utils.selector.eq('route', 'api_prom_push|loki_api_v1_push|/httpgrpc.HTTP/Handle')],
+                              dashboards['loki-writes.json'].clusterMatchers + dashboards['loki-writes.json'].matchers.distributor + [utils.selector.re('route', 'api_prom_push|loki_api_v1_push|/httpgrpc.HTTP/Handle')],
                             )
                           )
                         )