Bump grafana and grafana-enterprise versions used for GEL Helm env (#9368)

**What this PR does / why we need it**:
Bumps the version of Grafana/Grafana-Enterprise being used to what is
currently current.

**Which issue(s) this PR fixes**:
This gets rid of a warning displayed about "The current Grafana version
is not supported" in relation to the GEL plugin.

tools/dev/k3d/environments/helm-cluster/main.jsonnet

@@ -133,8 +133,8 @@ local tenant = 'loki';
 
   local dashboardsPrefix = if enterprise then 'enterprise-logs' else 'loki',
   local grafanaImage = if enterprise then
-    grafana.withImage('grafana/grafana-enterprise:8.2.5') else
-    grafana.withImage('grafana/grafana:8.2.5'),
+    grafana.withImage('grafana/grafana-enterprise:9.5.1') else
+    grafana.withImage('grafana/grafana:9.5.1'),
   grafana+: grafana
             + grafana.withAnonymous()
             + grafanaImage