[CI] Stable branch pipelines skip Docker image build job

Summary

Example:

• Pipeline: https://gitlab.com/gitlab-org/cloud-native/gitlab-operator/-/pipelines/448492054
• Failed job: https://gitlab.com/gitlab-org/cloud-native/gitlab-operator/-/jobs/1977543670

In CI pipelines for stable branches, the Docker image job is skipped. That means the Deployment fails to start because it can't pull the desired image.