v2: metastore client (#3540)

- metastore returns an error with a RaftLeader details
- metastore instances are discovered with k8s api instead of dns

Author: korniltsev

.mockery.yaml

@@ -11,9 +11,16 @@ packages:
   github.com/grafana/pyroscope/api/gen/proto/go/metastore/v1:
     interfaces:
       MetastoreServiceClient:
+      MetastoreServiceServer:
   github.com/grafana/pyroscope/api/gen/proto/go/querier/v1/querierv1connect:
     interfaces:
       QuerierServiceClient:
   github.com/grafana/pyroscope/pkg/frontend:
     interfaces:
       Limits:
+  github.com/grafana/pyroscope/api/gen/proto/go/compactor/v1:
+    interfaces:
+      CompactionPlannerServer:
+  github.com/grafana/pyroscope/pkg/experiment/metastore/discovery:
+    interfaces:
+      Discovery:

api/gen/proto/go/types/v1/types.pb.go

@@ -105,3 +105,7 @@ message GetProfileStatsResponse {
   // Milliseconds since epoch.
   int64 newest_profile_time = 3;
 }
+
+message RaftDetails {
+  string leader = 1;
+}