chore: Teporarily disabling sendToDeviceGroup integration test (#1292)

Author: hiranya911

test/integration/messaging.spec.ts

@@ -172,7 +172,7 @@ describe('admin.messaging', () => {
       });
   });
 
-  it('sendToDeviceGroup() returns a response with success count', () => {
+  xit('sendToDeviceGroup() returns a response with success count', () => {
     return admin.messaging().sendToDeviceGroup(notificationKey, payload, options)
       .then((response) => {
         expect(typeof response.successCount).to.equal('number');