packaging: setup: produce setup logs at /var/log

although setup logs are not of daemon, they used to be
stored at /var/log for future reference.

The location of the logs is set to
/var/log/ovirt-hosted-engine-setup/

Change-Id: Ic2fb666354bcf28b0d5b2b2cce0494b575b4461b
Signed-off-by: Sandro Bonazzola <sbonazzo@redhat.com>