Fix pip bundling

Not all pips should be their own transition. This CL
changes the rules so that any pip originally requested
by the system (even if done via the app -- eg legacy
pause+userLeaving) will not get their own transition
and instead be bundled into the current one.

This also fixes an issue where transient launch
committal was only entering pip for the new auto-enter
case but not the legacy userLeaving case.

Bug: 220196913
Bug: 231150615
Test: launch a legacy userLeave-enters-pip app and
      then go home (swipe or button).
Change-Id: I3c20341971ab4512509daa70314742f84c1ccd6b