packaging: Updated cleanup to ignore DB if --dont-drop-db supplied

This patch reverses the order for checking the DB presense and
for the 'drop_db' flag. First, we will check the option, and
if it was not supplied, the DB will not be checked nor touched.

Change-Id: I699573fa24fc8b60f67437a4ec3005ced820ff22
Bug-Url: https://bugzilla.redhat.com/888040
Signed-off-by: Alex Lourie <alourie@redhat.com>