Remove multiple starting windows within a transaction.

A transition can contain multiple tasks(e.g. split), so when the start
transaction of a transition applied, check and remove all
corresponding starting windows belong to the transition.

Flag: com.android.window.flags.remove_starting_in_transition
Bug: 413570098
Test: atest SwitchBetweenSplitPairsGesturalNavPortrait
Change-Id: I48546e52655e53498236c752109c4c09cae54c32