seperate PR to only include create API

Signed-off-by: Ruirui Zhang <[email protected]>

plugins/workload-management/src/main/java/org/opensearch/plugin/wlm/CreateQueryGroupResponse.java

@@ -77,12 +77,4 @@ public QueryGroup getQueryGroup() {
     public RestStatus getRestStatus() {
         return restStatus;
     }
-
-    /**
-     * restStatus setter
-     * @param restStatus - A {@link RestStatus} object
-     */
-    public void setRestStatus(RestStatus restStatus) {
-        this.restStatus = restStatus;
-    }
 }