codeintel: Add envvar to disable bloom filter tests

Created by: efritz

Add an environment variable to disable bloom filter tests for find reference and implementations queries.

We plan to disable bloom filters in Cloud to see if they, once a requirement for good performance when using SQLite, are a dominating overhead for some types of reference queries. If we see no negative changes in honeycomb for average queries and and we also see a positive improvement for the queries we're targeting, we can set this on-by-default and eventually deprecate the bloom filter code and data columns (which are actually quite sizeable in the database).

This is partial effort towards fixing #32328 (closed).

Test plan

Current CI tests. Should not affect any environment apart from Cloud, which we will enable only under surveillance.