Always notify of keyguard exit animation

When certain events, such as configuration changes, trigger between
keyguardGoingAway and setKeyguardShown, the starting the pending exit
animation will be cancelled and will notify the system of such an
occurance here. However, SystemUI never gets notified because applying
any occlusion state change returns early. Therefore, it is necessary to
always notify to start the animation to prevent an unrecoverable
inconsistent state.

Bug: 272274722
Test: manual
Change-Id: If1823781262a26d5bd2cfa8b86909e4f9892a717