Fix flaky missing stats test

[Jared Erwin (feordin)]

Description

Prevents GivenMissingTrueSearchForPatientByGender_NotExistsStatsAreCreated from failing based on test execution order. The test now checks only statistics introduced by the current search, while still detecting unintended resource-type fan-out.

Related issues

N/A.

Testing

the test in question is updated

FHIR Team Checklist

• PR title is succinct and less than 65 characters
• Add the sprint milestone
• CI is green before merge
• No system design assumptions changed; no ADR required
• Reviewed squash-merge requirements

Semver Change (docs)

Skip (test-only reliability fix)

[Codecov Comments Bot (codecov-commenter)]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 78.90%. Comparing base (20d379f) to head (d6ea403).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5786      +/-   ##
==========================================
+ Coverage   78.28%   78.90%   +0.61%     
==========================================
  Files        1016     1016              
  Lines       36940    36940              
  Branches     5619     5619              
==========================================
+ Hits        28920    29148     +228     
+ Misses       6644     6413     -231     
- Partials     1376     1379       +3     

see 10 files with indirect coverage changes

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