[EE] Make the 'Edit' links consistent in the issuable sidebar

EE MR for https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/16565

What does this MR do?

This makes the 'Edit' links in the issuable sidebar consistent.

Are there points in the code the reviewer needs to double check?

No need for the Sidebar| namespace for these generic links.

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• No need for a Changelog entry
• Review
  • Has been reviewed by Frontend
  • Has been reviewed by Backend
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• Internationalization required/considered
• If paid feature, have we considered GitLab.com plan and how it works for groups and is there a design for promoting it to users who aren't on the correct plan

What are the relevant issue numbers?

Related to https://gitlab.com/gitlab-org/gitlab-ce/issues/42190