pd: remove option from pd integration test (#3180)

Signed-off-by: okJiang <[email protected]>

prow-jobs/tikv/pd/latest-presubmits.yaml

@@ -39,7 +39,7 @@ presubmits:
       agent: jenkins
       decorate: false # need add this.
       always_run: true
-      optional: true
+      optional: false
       context: pull-integration-realcluster-test
       trigger: "(?m)^/test (?:.*? )?pull-integration-realcluster-test(?: .*?)?$"
       rerun_command: "/test pull-integration-realcluster-test"