Disable DND status change notification on watches.

Added a check to the showZenUpgradeNotification logic to detect the
presence of a watch.
Reupload of ag/4436427 which was reverted (ag/4466787) because I forgot to get
approvals from main Android team.

Bug: 74178001
Test: Flashed image to watch, saw expected behavior
Change-Id: If88df0fe2f3ecd0d6e075d56747ba32213bb2131