Do not recompute display config if its config frame is not changed

Since insetsDecoupledConfiguration is enabled, the display
configuration is no longer affected by insets. So if the insets are
changed, it only needs to update the override frame for legacy apps
and reports no change to the display.

Bug: 159103089
Flag: EXEMPT skip extra invocation
Test: DisplayPolicyTests#testUpdateDisplayConfigurationByDecor
Change-Id: I33b026ecee464d7d0b9417a32f871daf47f6fea5