Update overview panels to show Services instead of Interventions

[kevinrobinson]

This is part of #5.

This includes the main functional change and two other related improvements:

• update school overview page to show Services instead of Interventions
• fix STAR Reading slice panels
• stricter serialization when sending indexes to UI

School overview shows Services instead of Interventions

The main functional change is updating the school overview page from this:

to this:

Fix STAR Reading slice panels

In the process of making this change, there is a bunch of related cleanup and improvements. These include fixing up the related code for the STAR reading page, where there were regressions in the different ways users could slice cohorts of students (which had gone unnoticed since this isn't fully productionized yet):

STAR reading before:

STAR reading after:

Doing this simplified some code in schools_controller, and the factoring there splits the query that we can precompute daily (as part of #3) and the query for data that is likely to change more frequently.

Stricter serialization when sending indexes to UI

It also updates the serialization code for constant indexes in serialize_data_helper to filter out the fields we send down to the client. For service_types_index and other constants this just removes noise, but for educators_index it also stops exposing some mildly-sensitive information about other users (like their access level and potentially their phone number).

Before:

After: