(AppState) remove outdated TODO (facebook#34264)

Summary:
We are already returning the `remove` function, and the `removeEventListener` method has been removed in this PR: facebook#33580. So I believe this comment is now outdated and no longer relevant.

## Changelog

<!-- Help reviewers and the release process by writing your own changelog entry. For an example, see:
https://reactnative.dev/contributing/changelogs-in-pull-requests
-->

[Internal] [Removed] - Remove outdated TODO in AppState

Pull Request resolved: facebook#34264

Reviewed By: dmitryrykun

Differential Revision: D38120344

Pulled By: GijsWeterings

fbshipit-source-id: c6c4d42f5b631a67bb6ad49c14df1a772f1cc71b

Author: Antoine Doubovetzky

Libraries/AppState/AppState.js

@@ -82,11 +82,6 @@ class AppState {
     }
   }
 
-  // TODO: now that AppState is a subclass of NativeEventEmitter, we could
-  // deprecate `addEventListener` and `removeEventListener` and just use
-  // addListener` and `listener.remove()` directly. That will be a breaking
-  // change though, as both the method and event names are different
-  // (addListener events are currently required to be globally unique).
   /**
    * Add a handler to AppState changes by listening to the `change` event type
    * and providing the handler.