Merge pull request #34282 from ivanvc/mark-etcd-release-tests-as-blocking

etcd: set release-tests presubmit as blocking

Author: k8s-ci-robot

config/jobs/etcd/etcd-presubmits.yaml

@@ -577,7 +577,6 @@ presubmits:
         kubernetes.io/arch: arm64
 
   - name: pull-etcd-release-tests
-    optional: true # remove once the job is stable
     cluster: k8s-infra-prow-build
     always_run: true
     branches: