engine: Use standard audit log fields mechanism

No need to set fields using the method, we can use the standard
annotations mechanism.

Change-Id: I96acc0f97a5304838db51b91d7bc7c64678d0181
Bug-Url: https://bugzilla.redhat.com/907155
Signed-off-by: Mike Kolesnik <mkolesni@redhat.com>