Remove dead TryAuthOIDCRequestWithPrefix function

[kbukum1]

What are you trying to accomplish?

Remove dead code left behind after the OIDCRegistry migration (PRs #78–#92). The TryAuthOIDCRequestWithPrefix function in internal/oidc/oidc_credential.go was the old per-handler OIDC authentication pattern. All handlers now use OIDCRegistry.TryAuth() instead, leaving this function with zero callers anywhere in the codebase.

Cleaning this up reduces confusion for future contributors and removes unused dependencies from the file.

Anything you want to highlight for special attention from reviewers?

Removing the function also allows removing 4 imports that were only used by it: net/http, goproxy, helpers, and logging. The sync import is retained since it is still used by the OIDCCredential.mutex field.

The CreateOIDCCredential calls in cargo/hex/pub handlers (used as guard clauses to skip URL-less OIDC credentials) were reviewed and confirmed to be intentional, not dead code.

How will you know you have accomplished your goal?

• Confirmed zero callers via grep across the entire codebase
• go build ./... succeeds
• go test ./... passes (all packages)

Checklist

• I have run the complete test suite to ensure all tests and linters pass.
• I have thoroughly tested my code changes to ensure they work as expected, including adding additional tests for new functionality.
• I have written clear and descriptive commit messages.
• I have provided a detailed description of the changes in the pull request, including the problem it addresses, how it fixes the problem, and any relevant details about the implementation.
• I have ensured that the code is well-documented and easy to understand.

[Copilot]

Pull request overview

This PR removes unused legacy OIDC request-authentication code (TryAuthOIDCRequestWithPrefix) that was superseded by the OIDCRegistry migration, reducing confusion and cleaning up now-unneeded dependencies in the OIDC credential implementation.

Changes:

• Deleted the dead TryAuthOIDCRequestWithPrefix helper from internal/oidc/oidc_credential.go.
• Removed imports that were only used by that function (net/http, goproxy, helpers, logging).

Show a summary per file

File	Description
internal/oidc/oidc_credential.go	Removes legacy per-handler OIDC request auth helper and related unused imports, aligning with current OIDCRegistry.TryAuth usage.

Copilot's findings

• Files reviewed: 1/1 changed files
• Comments generated: 0