Add Auto DevOps build job for tags

What does this MR do?

This MR adds a new Auto DevOps build job for tags. Images built in the tag pipeline are named similarly to traditional image names.

Image name of gitlab-org/gitlab-ce master branch build:

registry.gitlab.com/gitlab-org/gitlab-ce/master:190a6a1e6728ff9425154fe9ccacaa75039854c7

Image name of gitlab-org/gitlab-ce v11.5.6 tag build:

registry.gitlab.com/gitlab-org/gitlab-ce:v11.5.6

What are the relevant issue numbers?

#17966 (moved), #42398 (moved), #53129 (moved)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated via this MR
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• Security reports checked/validated by reviewer