Avoid duplicated WindowContainerTransaction for TaskFragment

Before, when there is Task bounds change without triggering TaskFragment
bounds change, we may still trigger a WCT to update adjacentTF that
isn't different from the previous request.

Record the last request value to avoid duplicated request.

Also make sure the requested changes are reset when TaskFragment enters
PiP.

Bug: 265271880
Test: atest WmTests:TaskFragmentTest
Test: atest WMJetpackUnitTests:SplitPresenterTest
Change-Id: Ifd9bba2de3e5f2caaa3efd1a6af66f3bcebff7d1