Remove credentials from repo clone urls

Created by: arussellsaw

Originally we were going to drop this column, but the change is much simpler if we just remove the credentials from it instead.

There's a chance we can remove the batch changes dependency on this column, and then can drop the column without dependencies, so this work is a safety net for if we need to keep this around.

Originally i had planned to rename the field to RemoteURL but that broke far too many tests for me to spend time fixing today

https://sourcegraph.slack.com/archives/CHPC7UX16/p1618991621113500