Refactored JSON model generator build script

[ppatierno]

Within the "config-model-generator" project, the current Makefile "clean" target deletes the model JSON files and the calls the build-config-models.sh script by passing the "clean" arg.
The build-config-models.sh itself still deletes the model JSON file but when it gets the "build" arg instead.
So it seems that in both cases "clean" or "build" arg, what we do is removing the JSON model files.

This PR cleans a little bit the logic.
The removal of the JSON model file is put at the top of the build-config-models.sh so that it's always done.
At the same time, calling the build-config-models.sh is removed from the Makefile "clean" target because we can just rely on the exec-maven-plugin usage within the config-model-generator pom file.
When using maven "compile" or "clean", the build-config-models.sh is called with right arg ("build" and "clean").
So with the Makefile "clean" target just referring to the "java_clean" target, we end calling "mvn clean" which still leverages the exec-maven-plugin and calls the build-config-models.sh with "clean" arg.

In general the calling of the build-config-models.sh script is driven through the exec-maven-plugin and the deletion of JSNO model files is something we always want with every run (with both "clean" or "build" args).

All the above is, of course, valid when we use make clean and make build which anyway ends to use "mvn" the way described above.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.81%. Comparing base (13739b0) to head (44aa45c).
⚠️ Report is 5 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #12267      +/-   ##
============================================
+ Coverage     74.79%   74.81%   +0.01%     
- Complexity     6627     6629       +2     
============================================
  Files           376      376              
  Lines         25345    25345              
  Branches       3402     3402              
============================================
+ Hits          18958    18963       +5     
+ Misses         4998     4994       -4     
+ Partials       1389     1388       -1     

see 3 files with indirect coverage changes

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[ppatierno]

/gha run pipeline=regression

[github-actions]

⏳ System test verification started: link

The following 6 job(s) will be executed:

• regression-brokers-and-security-amd64 (oracle-vm-8cpu-32gb-x86-64)
• regression-operators-amd64 (oracle-vm-8cpu-32gb-x86-64)
• regression-operands-amd64 (oracle-vm-8cpu-32gb-x86-64)
• regression-brokers-and-security-arm64 (oracle-vm-8cpu-32gb-arm64)
• regression-operators-arm64 (oracle-vm-8cpu-32gb-arm64)
• regression-operands-arm64 (oracle-vm-8cpu-32gb-arm64)

Tests will start after successful build completion.

[github-actions]

🎉 System test verification passed: link

[scholzj]

Makes sense. Thanks.