CI：Fix autotest artifact download and matching

[stephamie7]

Summary

• Fix flocks-side autotest artifact download by not forwarding the GitHub PAT to the redirected storage URL.
• Send an exact expected artifact name to flocks_autotest and match artifacts by exact name instead of prefix.
• Add a short artifact lookup retry window and list available artifacts when the expected one is missing.

Testing

• Ran local workflow text checks for exact artifact-name wiring.
• Ran git diff --check.
• Did not trigger GitHub Actions from this branch.