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 85.71429% with 1 line in your changes missing coverage. Please review.

Project coverage is 84.84%. Comparing base (78f58dd) to head (bb99ed3).
Report is 1 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   84.78%   84.84%   +0.05%     
==========================================
  Files         111      111              
  Lines        5180     5167      -13     
==========================================
- Hits         4392     4384       -8     
+ Misses        624      620       -4     
+ Partials      164      163       -1     

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.8% Duplication on New Code

See analysis details on SonarQube Cloud