test: always use a unique directory for local advisory cases

[G-Rath]

Since #2445 has us stream bytes to and from disk rather than writing the entire contents in one go, it's no longer safe for tests to be using the databases in parallel so we always need to use a unique directory

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 67.79%. Comparing base (b806e83) to head (19a7f0d).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2451   +/-   ##
=======================================
  Coverage   67.79%   67.79%           
=======================================
  Files         172      172           
  Lines       13301    13301           
=======================================
  Hits         9018     9018           
  Misses       3573     3573           
  Partials      710      710           

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