Add debug logs for average processing time metric update

[josecelano]

Related to: #1589

Add more debug logs for the average processing time metric update.

I will deploy to the tracker demo and collect more data.

[josecelano]

ACK 520fd8b

[codecov]

Codecov Report

Attention: Patch coverage is 25.00000% with 3 lines in your changes missing coverage. Please review.

Project coverage is 85.12%. Comparing base (09f52e0) to head (520fd8b).

Files with missing lines	Patch %	Lines
...rver/src/statistics/event/handler/response_sent.rs	25.00%	1 Missing and 2 partials ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1592      +/-   ##
===========================================
- Coverage    85.14%   85.12%   -0.02%     
===========================================
  Files          287      287              
  Lines        22302    22306       +4     
  Branches     22302    22306       +4     
===========================================
+ Hits         18988    18989       +1     
- Misses        2992     2993       +1     
- Partials       322      324       +2     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.