Currently, all sessions get boosted any time DISPLAY_UPDATE_IMMINENT is
sent from SurfaceFlinger which can lead to large, unnecessary boosts.
This patch aims to change that by removing the wakeup behavior, relying
instead on sessions to boost themselves with new load change hints.
* Remove wakeup() from PowerHintSession
* Remove wakeSessions from PowerSessionManager
* Remove related timers and message handlers
* Remove DISPLAY_UPDATE_IMMINENT behavior entirely
Test: manual
Bug: b/260136431
Change-Id: I4610edfefe8fcbef7d4cdbf5768830a9392a54f7
c0f264b813