Check both parent and current windowing mode for legacy insets override

Currently, when animating between pip and fullscreen mode, the windowing
mode will be: task=pinned activity=fullscreen. If the insets override
only checks the mode from parent, the configuration will lose the
override when the activity still shows as fullscreen appearance, which
causes potential flickering. Especially if the display is close to
square, if the insets area are excluded or included in configuration,
it could even lead to orientation change that makes app uses different
layout during the pip animation.

Bug: 340035487
Test: adb shell am compat disable \
          INSETS_DECOUPLED_CONFIGURATION_ENFORCED pkg.pip.app
      adb shell wm size 2200x2200
      (make display be close to square)
      Enter/expand pip and check there is no extra
      configuration change when switching.
Merged-In: Ifa5e2da4478f89f6a95d15103bb01b29242421e2
Change-Id: Ifa5e2da4478f89f6a95d15103bb01b29242421e2
(cherry picked from commit 79ea1505)