Remove the state when forcefully remove overlay

The state check in PipTaskOrganizer#removeContentOverlay was added to
avoid double removal of the overlay. This has been addressed
alternatively by checking the leash state.

On the other hand, the state check does prevent the leash removal in the
fail-safe, since the state could have been set to undefined (since it's
moved from pip to full-screen).

Flag: EXEMPT bugfix
Bug: 352771711
Bug: 327405289
Test: restart Maps when it's entering PiP
Test: atest --iteration 5 \
      CtsWindowManagerDeviceOther:PinnedStackTests \
      FrameworksCoreTests:ActivityThreadTest \
      WmTests:ScreenshotTests \
      WmTests:TaskStackChangedListenerTest
Change-Id: I627d674128568b047e5b490252d2620307b6ab21