Fix `gitlab:ui:visual` to not run for docs

What does this MR do?

Fix gitlab:ui:visual to not run for docs

What are the relevant issue numbers?

The gitlab:ui:visual is using the anchor *except-docs to not run the job when it's a docs change, but since we are redefining expect in the job this is overrided, which results into the job running anyways when it's a docs change. For example https://gitlab.com/gitlab-org/gitlab-ce/pipelines/50890096

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