Update tooltip of detached label state

What does this MR do?

This MR is a port of https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/31917#note_204609902 on CE to update the text of the detached pipeline label.

Resolves https://gitlab.com/gitlab-org/gitlab-ce/issues/66061

Updates the tooltip of "detached" label/state to say "Pipelines for merge requests are configured. A detached pipeline runs in the context of the merge request, and not against the merged result. Learn more on the documentation for Pipelines for Merged Results."

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

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team