unified-storage: setup ring to shard requests (#103783)

* Updates the instrumentation_server service to use mux instead of the builtin router, and have it store the router in the module server: this is so we can register the /ring endpoint to check the status of the ring
* Create a new Ring service that depends on the instrumentation server and declares it as a dependency for the storage server
* Create standalone MemberlistKV service for Ring service to use
* Update the storage server Search and GetStats handler to distribute requests if applicable

pkg/modules/dependencies.go

@@ -5,7 +5,9 @@ const (
 	All string = "all"
 
 	Core                  string = "core"
+	MemberlistKV          string = "memberlistkv"
 	GrafanaAPIServer      string = "grafana-apiserver"
+	StorageRing           string = "storage-ring"
 	StorageServer         string = "storage-server"
 	ZanzanaServer         string = "zanzana-server"
 	InstrumentationServer string = "instrumentation-server"
@@ -13,8 +15,9 @@ const (
 )
 
 var dependencyMap = map[string][]string{
+	StorageRing:      {InstrumentationServer, MemberlistKV},
 	GrafanaAPIServer: {InstrumentationServer},
-	StorageServer:    {InstrumentationServer},
+	StorageServer:    {InstrumentationServer, StorageRing},
 	ZanzanaServer:    {InstrumentationServer},
 	Core:             {},
 	All:              {Core},