Disable flannel job until it works

hack/jenkins/diff-job-config-patch.sh

@@ -68,5 +68,8 @@ docker run --rm=true -i \
   bash -c "${common_commands}"
 
 diff -ruN "${output_dir}/upstream" "${output_dir}/patch" >"${diff_file}" || true
+if [[ -t 1 ]]; then  # Attached to a terminal?
+  less "${diff_file}"
+fi
 echo
 echo "  *** Diff saved in ${diff_file} ***"

hack/jenkins/job-configs/kubernetes-jenkins/kubernetes-e2e.yaml

@@ -511,6 +511,7 @@
                 export FAIL_ON_GCP_RESOURCE_LEAK="false"
         - 'gce-flannel':
             description: 'Run E2E tests on GCE using Flannel and the latest successful build. This suite is quarantined in a dedicated project because Flannel integration is experimental.'
+            disable_job: true  # Issue #24520
             # We don't really care to enforce a timeout for flannel tests. Any performance issues will show up in the other GCE builders.
             # This suite is to continuously check that flannel + Kubernetes works.
             timeout: 120