Harden set-default Checkout in e2e-versions.yml (persist-credentials: false)

The Checkout step in the set-default option job was the only one of 17
checkout steps in the workflow missing persist-credentials: false,
flagged by zizmor's artipacked audit. Align it with the rest of the file.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

.github/workflows/e2e-versions.yml

@@ -704,6 +704,8 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@v7
+        with:
+          persist-credentials: false
       - name: Setup Java 17 as default
         uses: ./
         id: setup-java-17