Refactoring, no functional change.
This commit refactors `send_e2ee_push_notification_apple`
and `send_e2ee_push_notification_android` to return a
`SentPushNotificationResult` dataclass.
It's a cleaner protocol than passing a mutable data structure
`delete_device_ids` as argument and updating it within
functions.
Fixes part of #35368.
(cherry picked from commit 3548764e21)
04352cd738