[CarPowerManager] Removed executor and added CompletableFuture

This will add an ability to cancel jobs on state transitions
while CPMS is waiting for dependant modules to complete.

Test: Manual
Bug: 112905910
Change-Id: Ib635f47129109abcc7912a71b55480751720b885
(cherry picked from commit 22eac44ee64ca93161c735ac09640a5a9f66916f)
3 files changed