Some performance improvements to the App Report

Set a facet size limit and don't include unnecessary facets. 

This along with https://github.com/dimagi/commcare-hq/pull/1791 (which this depends on) fixes issues with querying elasticsearch current in the app report. Also fixes issues with the slow loading UI.

tested by running the generated queries live on the prod es index

* [x] Merge https://github.com/dimagi/commcare-hq/pull/1791