Remove fetching of Realm notifications from /realms/slug/{realm_name} endpoint

[essential-randomness]

Problem

Fetching of Realm notifications is really slow and needs to be redesigned. Luckily, we already did some work splitting the "realm data fetching" endpoint (/realms/slug/{realm_name}) and the "realm notifications" endpoint (/realms/{realm_id}/notifications). However, the data fetching endpoint still uses the query that also fetches notifications, which is less than ideal.

Let's fix that!

The Players

• getRealmBoards is our entry point into the infamous "white whale query", the worst performing boba query that we have declared unfixable.
• This function is used in all realm data fetching queries, even the ones that don't need notifications.
• Likely, this wasn't changed even when I split the two endpoints cause I didn't want to redo the tests. I suspect that's going to be the "PITA" part of this fix.

Step by Step

• Zod the getRealmBoards query as data comes out of the database
• Zod the /realms/slug/{realm_name} endpoint
• Zod the /realms/{realm_id}/notifications endpoint
• Create a new (immediately-zodded) database query that gets all the boards in the realm with only the data effectively needed by the /realms/slug/{realm_name} endpoint
• Switch out the /realms/slug/{realm_name} endpoint to use that query
• Fix all tests (sorry)

Stretch

• Figure out if the getRealmBoards query is used in other parts of the codebase that don't need it.

The Future

While this gets fixed we'll be working on improving the performance of the notifications query by leveraging Redis.