Merge changes Ic2bb4798,I2a409de2,I88a50a0e,Ia69342a4,Ia6548e4d, ...

* changes:
  Use "commit" instead of "execute" for rollbacks.
  Rename PACKAGE_ROLLBACK_EXECUTED to ROLLBACK_COMMITTED.
  Remove unused RollbackManager APIs.
  Use RollbackManager.getAvailableRollbacks in RollbackTest
  Use new RollbackManager API in RollbackPackageHealthObserver.
  Add RollbackManager.getAvailableRollbacks API.
  Include all relevant packages in RollbackInfo.