don't call setIamPolicy if policy doesn't change
don't call setIamPolicy if policy doesn't change

PiperOrigin-RevId: 381139897
Change-Id: If43b777db8e536a46a27a99fc1a3a0bb006b7be4
GitOrigin-RevId: 21c6647b3f30c2eaa05e6af60d7fc2cdb0715fe8

deepmind/xmanager,deepmind/xmanager