Gitlab Runner: Make image registry separate configurable value

Package Merge Request

Package Changes

https://repo1.dso.mil/platform-one/big-bang/apps/developer-tools/gitlab-runner/-/blob/0.41.0-bb.1/CHANGELOG.md

Package MR

https://repo1.dso.mil/platform-one/big-bang/apps/developer-tools/gitlab-runner/-/merge_requests/60

For Issue

Closes https://repo1.dso.mil/platform-one/big-bang/apps/developer-tools/gitlab-runner/-/issues/39