Enforce leading-slash requirement on path parameters in ArtifactoryImpl

[fluxxBot]

• All tests passed. If this feature is not already covered by the tests, I added new tests.
• This pull request is on the dev branch.

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Summary

• Centralizes URI construction in ArtifactoryImpl behind a single buildUri(String path) helper
• buildUri validates that path starts with / before concatenating with the configured base URL, throwing IllegalArgumentException for invalid input
• Replaces seven independent URI.create(url + path) call sites (get, head, post, put, patch, delete, handleArtifactoryRequest) with the shared helper
• Adds unit test atPrefixedPathMustBeRejected covering malformed paths and confirming valid paths are unaffected

Also in this PR

• Fix CargoPackageTypeRepositoryTests: drop cargoInternalIndex and gitRegistryUrl from test settings — Artifactory 7.46.3 removed legacy Git index support for all Cargo repo types; sparse HTTP index is now the only accepted mode
• Fix CI workflow: add shell: bash to "Wait for Artifactory" and "Cleanup test repositories" steps so they run correctly on Windows runners; skip Artifactory-dependent steps on macOS where the local install does not start reliably

[github-actions]

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