s3-tests says goodbye to nose

most of rgw's test suites depend on the python nose library and, while we knew it was ancient and unmaintained, it was never worth the effort to rewrite tests. with python 3.9, nose stopped working entirely (https://github.com/nose-devs/nose/issues/1099), but everything still worked in upstream testing with older python. ubuntu 22.04 only ships python 3.10, so this has finally become a blocker for testing the reef release in https://github.com/ceph/s3-tests/pull/482, all of s3-tests' nose dependencies were replaced with pytest. https://github.com/ceph/ceph/pull/49826 was just merged to run that updated version in ceph's qa suites. we only validated that against the rgw suite, but i know there are other suites that run s3-tests - please let me know if any of those start failing other rgw tests that still need conversion to pytest: * src/test/rgw/rgw_multi/ * src/test/rgw/bucket_notification/ * https://github.com/ceph/ragweed