Drop the data.refresh_aggregates procedure and its issue_reporter_created_at materialized view

Turns out the legacy migrations included a procedure in the database that seemingly only ever refreshed the `issue_reporter_created_at` materialized view.

Since we are/will soon be versioning the materialized views, we should see if this is still needed.

At a MINIMUM we should drop this unused procedure since we have our own view refreshing process.

would be nice to drop the view too though since its only a think wrapper that basically just sorts the `issues` table