Apply the last recents animation transform on single-activity PIP tasks

- When swiping up to enter PIP w/ auto-enter, SysUI applies a transform
  on the leash which is seamlessly applied to the task (to prevent jumps
  when the leash is removed).  This was intended to be applied in both
  single and multiple activity PIP cases, but if that doesn't happen,
  then when the transform is later cleared, it will inadvertently reset
  the task's crop and matrix.

Bug: 201127015
Test: atest PinnedStackTests
Test: Open YT, enter PIP, turn screen off, turn screen back on
Change-Id: I0d6d46c7c52f7a43058902b50a26131f626ae92d