remove unused target param and __init__ from subclasses in the koji_import plugin
remove unused target param and __init__ from subclasses in the
koji_import plugin

* CLOUDBLD-7986

Signed-off-by: Robert Cerven <32de7a518694880140ad479fa3724b97728d8e88@redhat.com>

fr34k8/atomic-reactor,fr34k8/atomic-reactor,projectatomic/atomic-reactor,projectatomic/atomic-reactor