notifyKeyguardFlagsChanged in setShowWhenLocked

This causes a Transition to be executed immediately if something changed
on screen as a result of the client changing Activity.canShowWhenLocked
directly through setShowWhenLocked/setInheritShowWhenLocked.

Bug: 411544184
Test: KeyguardLockedTests#testShowWhenLockedActivity_removeAttr_hideImmediately
Flag: com.android.window.flags.fix_show_when_locked_sync_timeout
Change-Id: Ib55b3b1bc5f0a5189b6456533f56790d69617aad