simplify metrics settings

weed/pb/master.proto

@@ -23,6 +23,8 @@ service Seaweed {
     }
     rpc LookupEcVolume (LookupEcVolumeRequest) returns (LookupEcVolumeResponse) {
     }
+    rpc GetMasterConfiguration (GetMasterConfigurationRequest) returns (GetMasterConfigurationResponse) {
+    }
 }
 
 //////////////////////////////////////////////////
@@ -239,3 +241,10 @@ message LookupEcVolumeResponse {
     }
     repeated EcShardIdLocation shard_id_locations = 2;
 }
+
+message GetMasterConfigurationRequest {
+}
+message GetMasterConfigurationResponse {
+    string metrics_address = 1;
+    uint32 metrics_interval_seconds = 2;
+}