Import: Fix cyclic loading due to use of wrong save method (now)

* Replace doSaveAndResetLastChangeWasIntended with the standard doSave
  call to avoid cyclic execution of the runInWorkspace method.
* Regression w.r.t. #2140 does not occur.
* Remove doSaveAndResetLastChangeWasIntended as it is no longer needed.
  It was a workaround anyways.
* Use a non-Dirtying command to execute the migration service. We don't
  want to undo this step.

Issue-Ref: 3806
Issue-Url: https://af3-developer.fortiss.org/issues/3806


Signed-off-by: Alexander Diewald <diewald@fortiss.org>