SERVER-118429 introduced a step that clones the 10gen/mothra repo in order to map code owners to Jira teams for task assignment. 

The dependency on cloning this repo, however, can cause degraded GitHub performance to be exacerbated.

We should find an alternative that is more resilient, and use it instead.

(Perhaps a committed file is more appropriate after all, and have an Evergreen task on a cron that opens a PR to update it)