Whitelist ironic- prefix in filter.py
Whitelist ironic- prefix in filter.py

While ironic itself uses ir- prefix, ironic-inspector used ironic-.
This change will allow it to have better-looking logs in gate.

Change-Id: Id692f64c7fcf2e7c70c264e9a4e6f0d38d48a311

openstack-infra/os-loganalyze,openstack-infra/os-loganalyze,openstack-infra/os-loganalyze