[audio] Remove unnecessary PackageManager call

Clean up call to get packages in OpPlayAudio monitor which is
unnecessary and can lead to deadlock issues.

Instead, do not mute any non-app UID which is attempting to play audio
during zen.

Test: compiles
Bug: 338089555
Flag: EXEMPT cleanup
Change-Id: I5186e190bf52480f35436cce75abc8c506150fd9