Remove _shouldEmitEvent guardrails (facebook#45837)

Summary:
Pull Request resolved: facebook#45837

Some Internal tests in the old architecture were failing after landing [facebook#45414](facebook#45414) because the `RCTNativeAnimatedModule` in the old architecture was not declaring the event.

This change fixes it by declaring the event that is never fired in the Old Architecture as it is not needed.

## Changelog
[iOS][Added] - Declare the `onUserDrivenAnimationEnded` in the old Architecture

Reviewed By: sammy-SC

Differential Revision: D60499584

fbshipit-source-id: 581a30a88dbd6d8d67078a11699157c55ed19e58

packages/react-native/Libraries/NativeAnimation/RCTNativeAnimatedTurboModule.mm

@@ -27,9 +27,6 @@ @implementation RCTNativeAnimatedTurboModule {
   NSMutableArray<AnimatedOperation> *_preOperations;
 
   NSSet<NSString *> *_userDrivenAnimationEndedEvents;
-
-  // TODO: Remove this when https://github.com/facebook/react-native/pull/45457 lands
-  BOOL _shouldEmitEvent;
 }
 
 RCT_EXPORT_MODULE();
@@ -45,7 +42,6 @@ - (instancetype)init
     _operations = [NSMutableArray new];
     _preOperations = [NSMutableArray new];
     _userDrivenAnimationEndedEvents = [NSSet setWithArray:@[ @"onScrollEnded" ]];
-    _shouldEmitEvent = NO;
   }
   return self;
 }
@@ -379,27 +375,8 @@ - (void)animatedNode:(RCTValueAnimatedNode *)node didUpdateValue:(CGFloat)value
   [self sendEventWithName:@"onAnimatedValueUpdate" body:@{@"tag" : node.nodeTag, @"value" : @(value)}];
 }
 
-// TODO: Remove this when https://github.com/facebook/react-native/pull/45457 lands
-- (void)startObserving
-{
-  [super startObserving];
-  _shouldEmitEvent = YES;
-}
-
-- (void)stopObserving
-{
-  [super stopObserving];
-  _shouldEmitEvent = NO;
-}
-
-// ----
-
 - (void)userDrivenAnimationEnded:(NSArray<NSNumber *> *)nodes
 {
-  if (!_shouldEmitEvent) {
-    return;
-  }
-
   [self sendEventWithName:@"onUserDrivenAnimationEnded" body:@{@"tags" : nodes}];
 }