Modify PhoneWindowManager to avoid interfering with current user's experience

- There are several code locations that assume the operations are for
  the current user.
- However, these operations could be executed in reponse to requests
  for visible background users in MUMD environment.
- We should handle them to avoid interfering with current user's
  experience.

Bug: 358267540
Test: atest WmTests:PhoneWindowManagerTests
Flag: EXEMPT bugfix
(cherry picked from https://partner-android-review.googlesource.com/q/commit:bd7104e0e1abe78201a4adcf6ce3bbc1abc0b93f)

Change-Id: I21cff2407937d9de87108529a74d0e9e3f4ca4e8