[E2E] PROMOTE TO BLOCKING: add_comment_to_snippet_spec.rb

What does this MR do?

Promotes the following e2e tests to the blocking bucket:

1. Create Adding comments on snippets behaves like comments on snippets adds, edits, and deletes a comment on a personal_snippet | Testcase | Spec metrics

This MR was created based on data from reliable e2e test report: #456047 (closed)

(This MR was automatically generated by gitlab_quality-test_tooling at 2024-04-15 02:05:21 UTC)