Defer creating+sending SLEEP transitions

The SLEEP transition is a sync to wind down all animations since the
display isn't animating any more. Since SLEEP is forcibly merged into
existing transitions, this can be problematic when the screen is still
on during dream/keyguard because we need to let those animations finish
uninterrupted.

This lets us remove the special case extension for SLEEP timeouts for
keyguard animations and also makes some other cases like home swipe on
top of the lock screen work properly.

Test: atest CtsWindowManagerDeviceKeyguard:KeyguardTests
Bug: 293862576
Change-Id: Ic8416c303848fd96241a715a82dcf53a3561a2eb