API requests to /learn warn about lots of n+1 queries

[ChristopherChudzicki]

Steps to Reproduce

Noticed this recently and reminded me of Nathan's recent tech talk. Not sure if this is affecting performance, but it does seem like a lot of queries

1. On local, with Open Discussions running & courses populated visit http://od.odl.local:8063/learn
2. view web logs: docker compose logs --follow --no-log-prefix --tail 1000 web

Expected Behavior

No N+1 error warnings

Actual Behavior

Lots of n+1 query errors on various models

ERROR 19 [nplusone] notifiers.py:40 - [38f23fa2ae36] - Potential n+1 query detected on `Podcast.coursetopic_set`
ERROR 19 [nplusone] notifiers.py:40 - [38f23fa2ae36] - Potential n+1 query detected on `Podcast.coursetopic_set`