Give original session id to non-staged rollbacks (1/n)

* Reduce differences between staged and non-staged rollbacks
* Remove the possible conflicts between Rollback#mStagedSessionId and
  RollbackInfo#mIsStaged
* Now both staged and non-staged rollbacks can be searched using
  the original session ids.
* This is in preparation for unifying the flow of enabling rollback
  for both staged and non-staged rollbacks.

Bug: 183466803
Test: atest RollbackUnitTest RollbackStoreTest AppDataRollbackHelperTest
Test: atest RollbackTest CtsRollbackManagerTestCases
Test: atest MultiUserRollbackTest CtsRollbackManagerHostTestCases StagedRollbackTest

Change-Id: I54b737074c8b94780b54a0a552834f0a77f9c1a8