ee_compat_check job needs to be updated for forks

Currently, the job doesn't fetch from the forked remote.

For example here https://gitlab.com/siemens/gitlab-ce/-/jobs/33379833:

=> Fetching CE/fix/update-doorkeeper-openid-connect

$ git fetch https://gitlab.com/gitlab-org/gitlab-ce.git fix/update-doorkeeper-openid-connect