Remove policy search test, add conftest

[anth-volk]

Fixes #2146

This PR removes a test that fails 30-40% of the time purely due to race conditions introduced by its improper emission of data directly to the database that we embed locally into the API when deploying. This removes that and adds explicit recognition of the test directory's path within a new conftest.py file.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 77.07%. Comparing base (61742fb) to head (aa51ee8).
Report is 9 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2147      +/-   ##
==========================================
- Coverage   77.83%   77.07%   -0.77%     
==========================================
  Files          67       68       +1     
  Lines        2775     2757      -18     
  Branches      292      289       -3     
==========================================
- Hits         2160     2125      -35     
- Misses        553      571      +18     
+ Partials       62       61       -1     

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