Fix KeyguardController::mDisplayStates leak

ActivityDisplay#remove doesn't ensure this display be remove directly,
should move KeyguardController::onDisplayRemoved into releaseSelfIfNeeded.

Bug: 118238630
Test: atest ActivityManagerMultiDisplayTests#testNoLeakOnExternalDisplay.

Change-Id: Ia9619c59da8be736f71af1b8fddc14b4798c966e
1 file changed