Enable autocomplete on project snippets

What does this MR do?

EE MR, https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/2174

Enable autocomplete on project snippets

Why was this MR needed?

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/12108 disabled autocomplete for personal snippets and project snippets. But we want autocomplete on project snippets.

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 https://gitlab.com/gitlab-org/gitlab-ce/issues/33911