Fix isNotificationLaunchAnimationRunningOnKeyguard.

This flow was introduced in ag/26946263. When the keyguard_wm_state_refactor flag is enabled, it's used to determine whether the lockscreen is visible from a WM perspective.

Two issues weren't caught in the original CL review:
- We should be checking that isLaunchAnimationRunning=true as well as the finished state.
- We need to emit false onStart, or flows that combine this one won't emit until the next notification launch.

Bug: 278086361
Flag: ACONFIG com.android.systemui.keyguard_wm_state_refactor DEVELOPMENT
Test: manual
Change-Id: Idfe50983ff34b977b1e7ab84080f7a26ab016079