Fix issue with jumping PIP when IME shows.

- Removing extraneous content frame adjustment for the visible IME in
  WindowState, which conflicts with new IME adjustment logic in the
  PinnedStackController.

Bug: 36820637
Test: Launch YT PIP, bring up IME
Test: go/wm-smoke
Change-Id: I6d5e647aa0cd75ff48c1efff50cc42093dcb1129