Fix double metro banner in Bridgeless (#43967)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/43967

Following up https://github.com/facebook/react-native/issues/43943, the metro loading banner is presented twice in Bridgeless mode.

This happens because both the RCTInstance and the RCTHost are listening to the Reload Command and issuing the instructions to refetch the JSBundle and to present the banner.

The RCTInstance should not concern itself with lifecycle events, owned by the RCTHost.

## Changelog:
[iOS][Fixed] - Avoid to show Metro Loading banner twice.

Reviewed By: cortinico

Differential Revision: D55870640

fbshipit-source-id: addb67d3226f7d7db20736309172a42fc15f3aa3

packages/react-native/ReactCommon/react/runtime/platform/ios/ReactCommon/RCTInstance.mm

@@ -31,7 +31,6 @@
 #import <React/RCTModuleData.h>
 #import <React/RCTPerformanceLogger.h>
 #import <React/RCTRedBox.h>
-#import <React/RCTReloadCommand.h>
 #import <React/RCTSurfacePresenter.h>
 #import <ReactCommon/RCTTurboModuleManager.h>
 #import <ReactCommon/RuntimeExecutor.h>
@@ -136,11 +135,6 @@ void RCTInstanceSetRuntimeDiagnosticFlags(NSString *flags)
                           name:@"RCTNotifyEventDispatcherObserversOfEvent_DEPRECATED"
                         object:nil];
 
-    [defaultCenter addObserver:self
-                      selector:@selector(didReceiveReloadCommand)
-                          name:RCTTriggerReloadCommandNotification
-                        object:nil];
-
     [self _start];
   }
   return self;
@@ -519,9 +513,4 @@ void RCTInstanceSetRuntimeDiagnosticFlags(NSString *flags)
                      isFatal:error.isFatal];
 }
 
-- (void)didReceiveReloadCommand
-{
-  [self _loadJSBundle:[_bridgeModuleDecorator.bundleManager bundleURL]];
-}
-
 @end