chore: Remove support for v0 format

[thomaspoignant]

Description

This PR is removing the v0 format support from GO Feature Flag.

Warning

This PR should be merged when releasing a version that remove support for v0 format.
We should wait at least until v1.40.0 before releasing it.

Closes issue(s)

Resolve #2403 #2398

Checklist

• I have tested this code
• I have followed the contributing guide

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[codecov]

Codecov Report

Attention: Patch coverage is 83.33333% with 1 line in your changes missing coverage. Please review.

Project coverage is 86.56%. Comparing base (ed39a6e) to head (71b946e).
Report is 66 commits behind head on main.

Files with missing lines	Patch %	Lines
cmd/editor/main.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2496      +/-   ##
==========================================
+ Coverage   86.48%   86.56%   +0.08%     
==========================================
  Files         100      100              
  Lines        3544     3536       -8     
==========================================
- Hits         3065     3061       -4     
+ Misses        352      349       -3     
+ Partials      127      126       -1     

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[sonarcloud]

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 SonarCloud