packaging: setup: Rename /etc/sysconfig/ovirt-engine

During upgrade, after updating packages, we rename
/etc/sysconfig/ovirt-engine.rpmsave to /etc/sysconfig/ovirt-engine,
for preparation to a rollback if it's needed.

This change renames it back during closeup, after the transaction is
committed and we know we won't need it anymore.

Change-Id: Icab6f89ac0346db08591c8ede7a3bf68abeb8c40
Signed-off-by: Yedidyah Bar David <didi@redhat.com>