fix: Pass session_id to fieldmap finder

[effigies]

Closes #3558.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 72.88%. Comparing base (7273193) to head (863902e).
⚠️ Report is 3 commits behind head on maint/25.2.x.

Additional details and impacted files

@@              Coverage Diff              @@
##           maint/25.2.x    #3573   +/-   ##
=============================================
  Coverage         72.88%   72.88%           
=============================================
  Files                60       60           
  Lines              4820     4820           
  Branches            626      626           
=============================================
  Hits               3513     3513           
  Misses             1164     1164           
  Partials            143      143           

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