fix: unify the auth data handle to the decode method

[chlins]

Thank you for contributing to Harbor!

Comprehensive Summary of your change

Abstract a common unified method to ensure that when using a manager to obtain a provider, the auth information is correctly populated.

Issue being fixed

Fixes #21353

Please indicate you've done the following:

• Well Written Title and Summary of the PR
• Label the PR as needed. "release-note/ignore-for-release, release-note/new-feature, release-note/update, release-note/enhancement, release-note/community, release-note/breaking-change, release-note/docs, release-note/infra, release-note/deprecation"
• Accepted the DCO. Commits without the DCO will delay acceptance.
• Made sure tests are passing and test coverage is added if needed.
• Considered the docs impact and opened a new docs issue or PR with docs changes if needed in website repository.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 46.21%. Comparing base (c8c11b4) to head (01a2391).
Report is 341 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #21350      +/-   ##
==========================================
+ Coverage   45.36%   46.21%   +0.84%     
==========================================
  Files         244      247       +3     
  Lines       13333    13883     +550     
  Branches     2719     2875     +156     
==========================================
+ Hits         6049     6416     +367     
- Misses       6983     7131     +148     
- Partials      301      336      +35     

Flag	Coverage Δ
unittests	46.21% <ø> (+0.84%)	⬆️

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see 491 files with indirect coverage changes

[wy65701436]

lgtm

[Vad1mo]

I PR should have a description of the change and a reference to an issue or similar

[chlins]

@Vad1mo I've updated the description and created issue for it, pls take a look again, thanks.