[CI] Add a test-result folder in backend to help debug stream count issues.

[aHenryJard]

Proposed changes

It's hard to understand number different on counter without data reference on master. I propose to add a dump of event content in the JFrog archived artefact.

• add an test utily to dump data to file in a dedicated folder "test-results" (similar to frontend folder name)
• compress and send to JFrog

Related issues

No issue, it's out of band.
done in context of #9394

Checklist

• I consider the submitted work as finished
• I tested the code for its functionality
• I wrote test cases for the relevant uses case (coverage and e2e)
• I added/update the relevant documentation (either on github or on notion)
• Where necessary I refactored code to improve the overall quality

Further comments

After a "json format" locally, it gives a diff like this:

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 65.34%. Comparing base (1cafb54) to head (00c446d).
Report is 6 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #9480   +/-   ##
=======================================
  Coverage   65.34%   65.34%           
=======================================
  Files         624      624           
  Lines       59697    59697           
  Branches     6683     6690    +7     
=======================================
+ Hits        39010    39011    +1     
+ Misses      20687    20686    -1     

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