fix(api): participantCount query should match all instead of only most significant modalities

[nellh]

If the validator has matched a modality, include it in the participant count. Search was already adjusted to follow this behavior, this aligns the participant count values with the search query results.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 73.57%. Comparing base (dd5e5ff) to head (ae11504).
Report is 3 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3126      +/-   ##
==========================================
- Coverage   73.63%   73.57%   -0.07%     
==========================================
  Files          45       45              
  Lines        1631     1631              
==========================================
- Hits         1201     1200       -1     
- Misses        430      431       +1     

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