qa/suite: whitelist PG_AVAILABILITY in rados_api_tests.yaml

qa/suite: whitelist PG_AVAILABILITY in rados_api_tests.yaml

pg will be created when increasing pgp-num and pg-num. so at that
moment, PG_AVAILABILITY is reported. so whitelist it in all tests which
run rados/test.sh. that script exercises ceph_test_rados_api_list.

Fixes: http://tracker.ceph.com/issues/23763
Signed-off-by: Kefu Chai <kchai@redhat.com>
(cherry picked from commit cdcbd47e1e3aafe5d9217956b6db25144bd86c9f)

Conflicts:
	qa/suites/powercycle/osd/tasks/rados_api_tests.yaml
	qa/suites/rados/basic/tasks/rados_api_tests.yaml: trivial
resolution.