Add vulnerabilites to high traffic tables list

When working on
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/64704 it was
suggested that we add vulnerabilites table to our list of high traffic
table due to high adoption.

rubocop/rubocop-migrations.yml

@@ -42,6 +42,7 @@ Migration/UpdateLargeTable:
     - :user_details
     - :vulnerability_occurrences
     - :web_hook_logs
+    - :vulnerabilities
   DeniedMethods:
     - :change_column_type_concurrently
     - :rename_column_concurrently