Move auto build image repository name to a method

What does this MR do and why?

We(JH Team) got a failed pipeline which is caused by the missing of auto build image with correct version, see it here:

• Pipeline: https://jihulab.com/gitlab-cn/gitlab/-/pipelines/969053
• Job: https://jihulab.com/gitlab-cn/gitlab/-/jobs/6527515

Relevant background

• #353815

JH Issue and MR

• Issue: https://jihulab.com/gitlab-cn/gitlab/-/issues/2606
• MR: https://jihulab.com/gitlab-cn/gitlab/-/merge_requests/1420

The issue we're going to fix for JH

The image repository name is not matching with the actual one for JH

# current name in JH repo
"gitlab-org/cluster-integration/auto-build-image"

# expect one in JH repo
"gitlab-cn/cluster-integration/auto-build-image"

Solution

Differentiate the repository name for upstream and JH.

In this MR we change the auto build image repository name from a simple hard-coded string assignment to a method. By doing this, we can overwrite it in JH repo easily.