Merge branch 'add-issues-merge-requests-to-high-traffic-tables' into 'master'

Add `issues` and `merge_requests` to high traffic tables

See merge request gitlab-org/gitlab!32936

doc/development/migration_style_guide.md

@@ -367,6 +367,8 @@ migration involves one of the high-traffic tables:
 - `users`
 - `projects`
 - `namespaces`
+- `issues`
+- `merge_requests`
 - `ci_pipelines`
 - `ci_builds`
 - `notes`