notif: Inline `maybeSendPushToken` and simplify.
notif: Inline `maybeSendPushToken` and simplify.

This has just one caller, and they have some logic in common; folding
them together makes the code both shorter and easier to understand.

vishwesh3/zulip-mobile,vishwesh3/zulip-mobile,vishwesh3/zulip-mobile,vishwesh3/zulip-mobile