Fix native module lookup followup from D28630805

Summary:
In D28630805 (https://github.com/facebook/react-native/commit/f78526ce3d4004eb4bf8ca5178ca7e2c1c9abc1a) ([github link](https://github.com/facebook/react-native/pull/31457)) I added a setter to workaround a bug I perceived with `moduleRegistry`. Turns out - the proper fix was to remove the `synthesize` line. See conversation on linked diff for more context.

Changelog: [Internal]

Reviewed By: RSNara

Differential Revision: D29144717

fbshipit-source-id: aa95b670b540b9007eed76769c9babc10ea399ce

Libraries/Network/RCTNetworking.mm

@@ -155,7 +155,6 @@ static NSString *RCTGenerateFormBoundary()
 }
 
 @synthesize methodQueue = _methodQueue;
-@synthesize moduleRegistry = _moduleRegistry;
 
 RCT_EXPORT_MODULE()
 
@@ -190,14 +189,6 @@ RCT_EXPORT_MODULE()
   _responseHandlers = nil;
 }
 
-// TODO (T93136931) - Investigate why this is needed. This setter shouldn't be
-// necessary, since moduleRegistry is a property on RCTEventEmitter (which this
-// class inherits from).
-- (void)setModuleRegistry:(RCTModuleRegistry *)moduleRegistry
-{
-  _moduleRegistry = moduleRegistry;
-}
-
 - (NSArray<NSString *> *)supportedEvents
 {
   return @[@"didCompleteNetworkResponse",