Fix issue with do-not-pip and bookend transition

- When we are not using a bookend transition we see:
    Recents transient transition (T1) start
      .. recents animation finishes
      -> finishWct.setDoNotPip() called for all pausing tasks
    -> Recents transient transition (T1) end
    -> Transition finishes and checks T1's hiding containers
       for enter pip (finds do-not-pip flag)

  However, with the bookend transition set, the following occurs:
    Recents transient transition (T1) start
      .. recents animation finishes
      -> bookendWCT.setDoNotPip() called for all pausing tasks
      -> Recents bookend transition (T2) start w/ bookendWCT
    -> Recents transient transition (T1) merges bookend transition (T2)
    -> Recents transient transition (T1) end
    -> Transition finishes and checks T1's hiding containers
       for enter pip (no flag set because it was set on the WCT
       applied for T2)

  This CL changes the logic to apply setDoNotPip() on the transition
  that is transiently hiding the given container to ensure that it
  will find and respect the right flag when checked

Bug: 346588978
Flag: com.android.wm.shell.enable_recents_bookend_transition
Test: atest WmTests:TransitionTests
Test: atest WmTests:WindowOrganizerTests
Change-Id: Ibf2be8a3d0bea33fc916118681147b4bc5143715