app: reset feature flag gauge

[KaloyanTanev]

Similar issue to #4225

category: bug
ticket: none

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 56.92%. Comparing base (a44b143) to head (9bd7a2f).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
app/metrics.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4228      +/-   ##
==========================================
- Coverage   56.97%   56.92%   -0.06%     
==========================================
  Files         237      237              
  Lines       30689    30690       +1     
==========================================
- Hits        17485    17470      -15     
- Misses      10971    10989      +18     
+ Partials     2233     2231       -2     

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