Allow Home app to BAL during app switches

The tightened visibility check sometimes fails because the window
manager's app switch state is still/already disallowed when the home app
initiates certain actions (its purpose is to switch between apps).
So allowlisting the home app to ignore the stricter app switch
restriction.
This reverts the behavior for the home app back to the state before
enabling the balImproveRealCallerVisibilityCheck flag.

Test: atest BackgroundActivityLaunchTest
Bug: 323739101
Change-Id: Ic537c6fcb43e466e4df6d9383579cee33fccd060