Notify listeners when syncing group expansion mgr with the pipeline.

Fix: 293887828
Bug: 282865576
Bug: 293434635
Test: atest GroupExpansionManagerTest & manually verified with the flag
on and off
Flag: NOTIFICATION_GROUP_EXPANSION_CHANGE

Change-Id: I105d710d745ba6e998cdf63ec7b14156f525c2a1
3 files changed