fix(helmvalues): write helm image-name with or without registry url

[chengfang]

Assisted-by: Cursor

Fixes #974 in master branch, by applying the fix in PR #1312 from master-annotation-based branch

[codecov-commenter]

Codecov Report

❌ Patch coverage is 85.29412% with 10 lines in your changes missing coverage. Please review.
✅ Project coverage is 70.69%. Comparing base (7ae5ee4) to head (0d6763f).

Files with missing lines	Patch %	Lines
pkg/argocd/update.go	83.92%	5 Missing and 4 partials ⚠️
registry-scanner/pkg/image/image.go	91.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1319      +/-   ##
==========================================
+ Coverage   70.48%   70.69%   +0.20%     
==========================================
  Files          49       49              
  Lines        4456     4522      +66     
==========================================
+ Hits         3141     3197      +56     
- Misses       1122     1128       +6     
- Partials      193      197       +4     

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