Don't reset mWindowsInsetsChanged

It should only be modified when the state of mInsetsChanged of a window
is changed, or when a window is removed. Otherwise, we might fail to
send INSETS_CHANGED unexpectedly.

Bug: 311026631
Bug: 315500042
Test: presubmit
Change-Id: Ie72dfc25844e483c681e173cd8e0c3967d2297a6