Adds backport change for `pipeline.scss` updates

What does this MR do?

This is the CE backport for the changes made in gitlab-ee!11633. It is an update of !27698 (closed), which was closed when the branch was renamed.

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Performance and testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers