Remove unused _callbacks hashmap (#33097)

Summary:
Stumbled upon this unused code.

## Changelog

[Internal] [Fixed] - Remove unused _callbacks hashmap

Pull Request resolved: https://github.com/facebook/react-native/pull/33097

Test Plan: Test it still builds

Reviewed By: philIip

Differential Revision: D34215314

Pulled By: ShikaSD

fbshipit-source-id: 7357a9be725d57b37f697f7222b95c1fd1d9f67c

React/CoreModules/RCTActionSheetManager.mm

@@ -23,11 +23,7 @@ using namespace facebook::react;
 @interface RCTActionSheetManager () <UIActionSheetDelegate, NativeActionSheetManagerSpec>
 @end
 
-@implementation RCTActionSheetManager {
-  // Use NSMapTable, as UIAlertViews do not implement <NSCopying>
-  // which is required for NSDictionary keys
-  NSMapTable *_callbacks;
-}
+@implementation RCTActionSheetManager
 
 RCT_EXPORT_MODULE()
 
@@ -64,10 +60,6 @@ RCT_EXPORT_METHOD(showActionSheetWithOptions
     return;
   }
 
-  if (!_callbacks) {
-    _callbacks = [NSMapTable strongToStrongObjectsMapTable];
-  }
-
   NSString *title = options.title();
   NSString *message = options.message();
   NSArray<NSString *> *buttons = RCTConvertOptionalVecToArray(options.options(), ^id(NSString *element) {