[RC][FA] Move mutex usage (#29974)

comp/remote-config/rcclient/rcclientimpl/rcclient.go

@@ -311,9 +311,6 @@ func (rc rcClient) agentConfigUpdateCallback(updates map[string]state.RawConfig,
 // The RCClient can directly call back listeners, because there would be no way to send back
 // RCTE2 configuration applied state to RC backend.
 func (rc rcClient) agentTaskUpdateCallback(updates map[string]state.RawConfig, applyStateCallback func(string, state.ApplyStatus)) {
-	rc.m.Lock()
-	defer rc.m.Unlock()
-
 	wg := &sync.WaitGroup{}
 	wg.Add(len(updates))
 
@@ -332,9 +329,11 @@ func (rc rcClient) agentTaskUpdateCallback(updates map[string]state.RawConfig, a
 				return
 			}
 
+			rc.m.Lock()
 			// Check that the flare task wasn't already processed
 			if !rc.taskProcessed[task.Config.UUID] {
 				rc.taskProcessed[task.Config.UUID] = true
+				rc.m.Unlock()
 
 				// Mark it as unack first
 				applyStateCallback(configPath, state.ApplyStatus{
@@ -373,6 +372,8 @@ func (rc rcClient) agentTaskUpdateCallback(updates map[string]state.RawConfig, a
 						State: state.ApplyStateUnknown,
 					})
 				}
+			} else {
+				rc.m.Unlock()
 			}
 		}(originalConfigPath, originalConfig)
 	}