Use current insets source visibility for display switch

The preserved insets is a snapshot from display's insets state,
so it may store an invisible insets source if keyguard becomes
active when folding. Then when unfolding to apps, the restored
insets should respect the requested visibility from apps.

Fix: 433656558
Flag: EXEMPT BUGFIX
Test: atest DisplayPolicyTests#testSwitchDecorInsets
Test: Set fold mode to "Swipe up to continue".
      Set navigation mode to 3 button.
      Unfold the device, the app should get visible navbar insets.
Change-Id: If462a4c5432102f5425c2e7189093622ca9ea402