Fix issue with updating canAffectSystemUiFlags when swiping up with PIP

- The previous change reverted to resetting the flag when cleaning
  up the task, so we can remove the other path to reset the flag
- The original intent was to reset the flag when entering PIP, so
  it should be in the likelyResolvedMode == WINDOWING_MODE_PINNED
  block and not the currentMode == WINDOWING_MODE_PINNED block

Bug: 184703546
Test: Verify when entering PIP that we set canAffectSysUiFlags=false
      on transferring the leash, and then back to true when it enters
      PIP
Change-Id: I4c3ef81b6cecde14117a4d75ae1423456ff65f6a