Loki: Stop running tickers on deletes (#8697)

**What this PR does / why we need it**:
Calls `ticker.Stop()` to avoid leaking ticker resources for
`GenNumberLoader` and `deleteRequestsClient`.

pkg/storage/stores/indexshipper/compactor/deletion/delete_requests_client.go

@@ -94,6 +94,7 @@ func (c *deleteRequestsClient) Stop() {
 
 func (c *deleteRequestsClient) updateLoop() {
 	t := time.NewTicker(c.cacheDuration)
+	defer t.Stop()
 	for {
 		select {
 		case <-t.C:

pkg/storage/stores/indexshipper/compactor/generationnumber/gennumber_loader.go

@@ -48,6 +48,7 @@ func NewGenNumberLoader(g CacheGenClient, registerer prometheus.Registerer) *Gen
 
 func (l *GenNumberLoader) loop() {
 	timer := time.NewTicker(reloadDuration)
+	defer timer.Stop()
 	for {
 		select {
 		case <-timer.C: