Adding recents to stopping if the preload success

The recents activity could be removed from the hierarchy if
the preload was failed. And the activity will be leaked in the
stopping list since it was added to the list in the end of the
preload process.

Bug: 322752270
Test: wm presubmit
Change-Id: Id963c2e8d1c3d87e4c6c09c1debe0be335077fb9