packaging: allign user instruction for database creation with dwh

Allign the database creation instrutions to the setup user with dwh-setup.
replaced "create user..." with "create role...".

Change-Id: I98e0687ae9581c2378ca255f047597eb6b1d910b
Signed-off-by: Ofer Schreiber <oschreib@redhat.com>
Bug-Url: https://bugzilla.redhat.com/1059357
(cherry picked from commit c0f6e1a23a2f2f68136e5c501b4ec7ff08ebce3a)