Resolve pip window centering issue

Issue: The pip window would move to center when activating expansion
params while in regular pip mode. updateGravityOnExpansionToggled was
being called in onExpandedAspectRatioChanged without checking if
expansion was supported on the devices. Added this check before
proceeding with expansion logic.

Test: manual
Bug: 436351254
Flag: EXEMPT BUGFIX

Change-Id: Ib54b3f5375c81e7bfe43c553f2f4035112d78d3c