protect regex brackets for specifying just conformance tests

Author: dims

playbooks/cloud-provider-openstack-acceptance-test-e2e-conformance/run.yaml

@@ -95,7 +95,7 @@
               --deployment=local \
               --provider=local \
               --ginkgo-parallel=1 \
-              --test_args="--ginkgo.focus=[Conformance]" \
+              --test_args="--ginkgo.focus=\\[Conformance\\]" \
               --timeout=120m
         executable: /bin/bash
         chdir: '{{ zuul.project.src_dir }}'