Explicitly reset the task bounds when removing PIP

- Otherwise the task bounds are reset by WM, but the activity config is
  not updated until it's next started again resulting in a weird
  animation

Change-Id: I6e5aadd3481b7a5c1929d068c78c3ed1a7f6494b
Bug: 157749854
Test: atest PinnedStackTests
1 file changed