Remove Notification from clock STL.

Removes the notification from the clock STL. Also remove some redundant
composable invocations by adding additional reusable functions.

Test: look at compose LS landscape and potrait with centering animation.
Flag: ACONFIG com.android.systemui.compose_lockscreen DEVELOPMENT
Bug: 301968149

Change-Id: I19aa4c5344cb3af4371098f94f0383bcd85d86a0