Remove redundant warnings about notifications without message infos that exceed limits

Summary:
this differential removes unecessary warnings. We don't have to check if notification exceeds FCM/APN size limits after messageInfos removal. The reason for this is that we construct notification body based on ResolvedNotifTexts, which trims
texts in notification: https://github.com/CommE2E/comm/blob/master/lib/shared/notif-utils.js#L50-L57.

Test Plan:

1. Build iOS and Android apps.
2. Send large (more than 8000 characters) notification from web.
3. Ensure that notification is displayed on both devices.
4. Kill keyserver.
5. Open both apps.
6. Ensure notifications weren't persisted (since no messageInfos).

Reviewers: tomek

Reviewed By: tomek

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D8695