Don't kill process when overlay changed

Since PACKAGE_CHANGED will be sent after OVERLAY_CHANGED,
if dont-kill-app is always false when sending PACKAGE_CHANGED,
non-persistent apps are always got killed and have no chance
to handle application info changed during runtime.

Bug: 143138994
Bug: 140790688
Bug: 136085555
Test: atest OverlayManagerPerfTest
Change-Id: I7bde52a19a8c513af10ae300ba99d25a64acb88b