fix: provide cross-repo token for auto-testing checkout (#6831)

The test workflows checkout the private rustfs/auto-testing repository, but
the default GITHUB_TOKEN only has access to rustfs/rustfs, so every checkout
failed with 'repository ... not found' (nightly runs on 2026-08-28).

Pass secrets.PF_TESTING_GH_TOKEN (the existing cross-repo PAT already used
by the performance workflow) to the auto-testing checkout steps in all three
workflows.

.github/workflows/rustfs-performance-test.yml

@@ -96,6 +96,7 @@ jobs:
           ref: main
           path: auto-testing
           persist-credentials: false
+          token: ${{ secrets.PF_TESTING_GH_TOKEN }}
 
       - name: Show environment
         run: |