fix: Port #18133 to support Docker config for oras client

[frekw]

This backports the fix in #18133 to fallback to the local Docker config (~/.docker/config.json) in the absence of other credentials.

This should make private OCI repositories like Google's Artifact Registry work via Docker credential helpers like docker-credential-gcr, allowing authentication to seamlessly happen via workload identity.

I believe this is small enough not to need an enhancement proposal, but will happily create one if you disagree!

Checklist:

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 62.60%. Comparing base (414a178) to head (d5e70c3).
⚠️ Report is 502 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #25614      +/-   ##
==========================================
+ Coverage   62.59%   62.60%   +0.01%     
==========================================
  Files         353      353              
  Lines       49871    49876       +5     
==========================================
+ Hits        31216    31225       +9     
+ Misses      15669    15667       -2     
+ Partials     2986     2984       -2     

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[blakepettersson]

This PR seems to be the exact same one (to the point that there is no diff) of #25565

[frekw]

You’re absolutely right, I was unaware of it. Just spent a couple of hours tearing my hair until realizing what the problem was.

I’ll close this in favor of #25565