Make onLifecycleEvent broadcasting sequential.

When onLifecycleEvent is called multiple times, it is possible that listeners will receive the events in a different order. This is due to the multiple calls to the broadcast method.
To ensure correct behavior, a new executor is used to run broadcast execution sequentially.

Bug: 427938935
Test: cts
Flag: EXEMPT bugfix
Change-Id: Icd05e1b4c608e9c23c4aafdea26dc4c47f6f1660