codeintel: Add indexes to codeintel database tables

Created by: efritz

I'm not sure how fart-brained I was to have this happen, but I made the code intel tables without any primary keys or indexes. And we're already heavily into the migration (and have been writing only to Postgres for the past few days).

I've created these indexes on the production instance by hand so it wouldn't block the startup of any pods.

Todo:

• Ensure prod settings and this migration match
• Manually bump the codeintel_schema_migrations version
• Remove temp_file_limit setting applied manually in UI