Fix BuildButtonColumn icon.js to check rsp.status === 201

This fix was missing from the current branch. It ensures that only
201 Created responses are treated as successful builds, preventing
false 'Build scheduled' notifications when builds are rejected.

Author: LakshyaBagani

core/src/main/resources/hudson/views/BuildButtonColumn/icon.js

@@ -14,7 +14,7 @@ Behaviour.specify(
         method: "post",
         headers: crumb.wrap({}),
       }).then((rsp) => {
-        if (rsp.ok) {
+        if (rsp.status === 201) {
           notificationBar.show(message, notificationBar.SUCCESS);
         } else {
           notificationBar.show(failure, notificationBar.ERROR);