Merge changes from topic "revert-16575908-dont_abandon_child_qt_dev-VVMFNIYZZO" into qt-dev

* changes:
  [RESTRICT AUTOMERGE] Revert "Revert "Revert "[pm] remove old stage dirs on low storage"""
  [RESTRICT AUTOMERGE] Revert "Don't abandon child sessions (1/n)"
  [RESTRICT AUTOMERGE] Revert "Fix NPE"