Running tests using a custom image does not use associated QA image
Description
When running tests against a custom image, not hosted on a Docker Hub, like registry.gitlab.com/gitlab-org/omnibus-gitlab/gitlab-ce:SHA
it still tries to pull gitlab/gitlab-qa:SHA
instead of registry.gitlab.com/gitlab-org/omnibus-gitlab/gitlab-qa:ce-SHA
.
It makes it more difficult to test against a custom image locally.
Description to be extended.