Remove dead code
Remove dead code

This code, present since the original version of the cli_containerbuild
module, has never been used.

Neither repo_id nor skip_tag have ever appeared elsewhere in the
project. The condition can never have evaluated as truthy.

Signed-off-by: Tim Waugh <fe049355006bf7fdd11c5e47ffe7a5032af30704@redhat.com>

release-engineering/koji-containerbuild,release-engineering/koji-containerbuild