Facilitate testing PRs from an external repo hosted on GH

Closes #129 (closed)

This will enable us to define the upstream and downstream repos along with their respective branches that need to be set as an external repo (i.e. hosted external to gitlab for eg. Github) for this project to function.

changed milestone to %A/B testing

added Sprint 24-23 label

assigned to @atlurie

changed the description

changed title from Use vars to setup external repo in .gitlab-ci.yml to Use vars to setup external repo in .gitlab-ci.yml and test it's PRs

changed title from Use vars to setup external repo in .gitlab-ci.yml and test it's PRs to Facilitate testing PRs from an external repo hosted on GH

Follow !122 (merged) . Closing this because of change in the branch name. Rest is all identical.

closed