RFC 211: Repos added by user owned external services should be indexed

Created by: ryanslade

Public repos added by user owned external services should always be synced.

Confirm that listing default repos is only used by Zoekt on Cloud: https://github.com/sourcegraph/sourcegraph/blob/05db081805ef89db3f58c53bac3d4f0307e4d00d/internal/db/default_repos.go#L34

If so, update the query so that it also includes public repos added by users.