feat: disable direct channels API on iOS, fixes #3674

[MrLoh]

Description

As discussed in #3674 Direct Channel API on iOS was deprecated, so the SDK shouldn't set shouldEstablishDirectChannel = YES anymore. I tested that this doesn't affect the delivery of notifications on iOS.

Related issues

Fixes #3674

Release Summary

Remove support for deprecated iOS Direct Channel API (#3674)

Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
  • Yes
• My change supports the following platforms;
  • Android
  • iOS
• My change includes tests;
  • e2e tests added or updated in packages/\*\*/e2e
  • jest tests added or updated in packages/\*\*/__tests__
  • I have updated TypeScript types that are affected by my change.
• This is a breaking change;
  • Yes
  • No

Test Plan

Tested that notifications (including those with data payloads) still arrive on iOS in all 3 states (killed, background, running)

[CLAassistant]

All committers have signed the CLA.

[MrLoh]

There is a comment related to shouldEstablishDirectChannel here:

react-native-firebase/packages/messaging/ios/RNFBMessaging/RNFBMessaging+FIRMessagingDelegate.m

Lines 66 to 68 in 4889c7a

	// Receive data messages on iOS 10+ directly from FCM (bypassing APNs) when the app is in the foreground.
	// To enable direct data messages, you can set [Messaging messaging].shouldEstablishDirectChannel to YES.
	- (void)messaging:(nonnull FIRMessaging *)messaging didReceiveMessage:(nonnull FIRMessagingRemoteMessage *)remoteMessage {

I think it can just be removed, but maybe @Salakar or @Ehesp who have the git blame for this can advice.

[mikehardy]

@Salakar / @Ehesp the related link has the discussion but the change is nearly trivial, if you take as given that direct channel is going away upstream (it is), then setting this as the default is the thing to do