Disable autocomplete on snippets comments

What does this MR do?

EE MR: https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/2167

• Disable autocomplete on snippets comments

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

Was supposedly previously fixed here https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/11278/diffs

Not sure how this regressed 😕

I see that this "enabled" it again, https://gitlab.com/gitlab-org/gitlab-ce/commit/b050b68189e4cb674b1ef2760a5c4c6f798a114d#b4187b8866d35a7a17719280b5511d7fba8ec9fd_13_12 but I don't think this actually changed anything because the global GfmAutoComplete in dispatcher.js with everything enabled was still applying in that previous MR.

See where we first introduced comments in snippets, https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/11090/

Why was this MR needed?

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes #33594 (closed)