fix(upload): omit artifacts distribution URL for local --artifact-results folder

[jajreidy]

What
For --artifact-results as a single local folder (no comma), repository setup already skips the artifacts repository. Distribution URL building still added a synthetic artifacts pulp-content entry to the URL map and into pulp_results.json distributions. This change threads skip_artifacts_repo through DistributionManager.get_distribution_urls / PulpHelper.get_distribution_urls and sets it from get_distribution_urls_for_upload_context when artifact_results is folder mode, so artifacts is not listed alongside the skipped repo.

Why
Keeps behavior consistent: no artifacts repo or distribution when results JSON is only written locally.

How to test

git fetch origin
make lint
pre-commit run --all-files
make test
make test-diff-coverage

Notes for reviewers

• Konflux form url_path,digest_path (comma) is unchanged.
• CHANGELOG.md updated under [Unreleased] → Changed.
• Files: distribution_manager.py, pulp_helper.py, models/context.py, tests, CHANGELOG.md.

[snyk-io]

✅ Snyk checks have passed. No issues have been found so far.

Status	Scan Engine	Critical	High	Medium	Low	Total (0)
✅	Code Security	0	0	0	0	0 issues

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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.01%. Comparing base (0e424ea) to head (cb4603e).
⚠️ Report is 108 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #91      +/-   ##
==========================================
+ Coverage   95.53%   97.01%   +1.47%     
==========================================
  Files          70       74       +4     
  Lines        3946     5356    +1410     
==========================================
+ Hits         3770     5196    +1426     
+ Misses        176      160      -16     

Flag	Coverage Δ
unit-tests	97.01% <100.00%> (?)
unittests	?

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
pulp_tool/models/context.py	100.00% <ø> (ø)
pulp_tool/utils/distribution_manager.py	100.00% <100.00%> (ø)
pulp_tool/utils/pulp_helper.py	100.00% <100.00%> (ø)

... and 4 files with indirect coverage changes

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