Fix PhoneWindowManagerTests

The power short press unit tests related to the glanceable hub exercise
a code check that checks if the lock screen is disabled. Keyguard is
always disabled in test harness mode, meaning that automated runs of
these tests always fail, while local repros with atest did not.

Bug: 402588489
Fixes: 402588489
Test: atest PhoneWindowManagerTests
      enter test harness mode first with adb shell cmd testharness enable
Flag: NONE test fix
Change-Id: I6e600cc5906843112ebe0670df935dfcf28f9fc3