chore(warehouse): enrich discovery logs

[hiddeco]

Related to #1984

This brings the logging for Git and Helm artifact discovery up to the same level as what was already done for container images. Providing much richer data on trace level, and more structured information at the debug level.

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[codecov]

Codecov Report

Attention: Patch coverage is 66.66667% with 19 lines in your changes are missing coverage. Please review.

Project coverage is 45.68%. Comparing base (473eacd) to head (601e830).

❗ Current head 601e830 differs from pull request most recent head 8f4705f

Please upload reports for the commit 8f4705f to get more accurate results.

Files	Patch %	Lines
internal/controller/warehouses/git.go	73.33%	6 Missing and 2 partials ⚠️
internal/image/newest_build_selector.go	0.00%	5 Missing ⚠️
internal/controller/warehouses/images.go	75.00%	4 Missing ⚠️
internal/controller/warehouses/helm.go	66.66%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2035      +/-   ##
==========================================
- Coverage   45.79%   45.68%   -0.12%     
==========================================
  Files         236      234       -2     
  Lines       16077    16042      -35     
==========================================
- Hits         7362     7328      -34     
+ Misses       8355     8354       -1     
  Partials      360      360              

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[krancour]

LGTM after conflicts are resolved