invenio-recreate-demo-site: add bibsched user

* Specifies CFG_BIBSCHED_PROCESS_USER to be equal to
  CFG_INVENIO_USER in order to avoid guessing user
  identity (which could in some conditions go wrong).

Co-authored-by: Tibor Simko <tibor.simko@cern.ch>
Signed-off-by: Tibor Simko <tibor.simko@cern.ch>