Clean-up indexes from Topics

Overview

In #463254 (closed) we introduced the topics.organization_id column. With that, we had to add some indexes to support this new column.

Deliverables

• Remove the indexes that are backed-up by the ones that support organization_id column;
• • Use this graph to check if old indexes are still being picked by the PG query planer;
• Add any missing indexes that are not covering the organization_id column;

Follow up from #463254 (closed)