Clean up hiding while occluded.

We were passing empty params to handleStartKeyguardExitAnimation, without actually starting the animation. This ultimately short circuits, with the only real effects being calls to keyguardViewController#hide and onKeyguardExitFinished(). It's much more clear if handleStartKeyguardExitAnimation is only called
to... handle starting the keyguard exit animation.

There's one remaining use of empty handleStartKeyguardExitAnimation
in handleSetOccluded; I'll fix that in a followup just in case this
CL causes issues.

Bug: 272316191
Test: unlock from camera with remote animations enabled/disabled
Change-Id: Ida4f342fc06b3dcfa1c0e4e8ef45acddd37a586b