Modifies the interface to add search index metrics and initialises metrics first so it can be used from elasticsearch (#13663)

einterfaces/metrics.go

@@ -45,4 +45,7 @@ type MetricsInterface interface {
 	ObservePostsSearchDuration(elapsed float64)
 	ObserveStoreMethodDuration(method string, success string, elapsed float64)
 	ObserveApiEndpointDuration(endpoint string, elapsed float64)
+	IncrementPostIndexCounter()
+	IncrementUserIndexCounter()
+	IncrementChannelIndexCounter()
 }