database: include src.fedoraproject.org repos in ListIndexable

Created by: tsenart

Ideally we'd want Fedora project to be an org in Sourcegraph.com, but we don't yet support any other code hosts than github.com or gitlab.com, and search contexts aren't integrated with this code path, so we choose the hacky, yet simpler, change.

Part of #28028 (closed)