packaging: setup: honouring engine DB parameters from answer file

Honouring engine DB parameters if present in the answer file.

Bug-Url: https://bugzilla.redhat.com/1139211

Change-Id: I9a7f79f3da05d89b34fa2cc4f74ed628fb44e3b4
Signed-off-by: Simone Tiraboschi <stirabos@redhat.com>