qa/s3tests: filter on 'sts_tests' and 'webidentity_tests'

qa/s3tests: filter on 'sts_tests' and 'webidentity_tests'

qa/tasks/s3tests.py was adding `not test_of_sts` and `not
webidentity_test` by default, and the rgw/sts suites were adding
those attrs back in `extra_attrs`

when `extra_attrs` was changed to be additive, this started causing
InvocationError failures

instead of using `extra_attrs` to control these filters,
qa/tasks/s3tests.py now uses the `sts_tests` and `webidentity_tests`
flags from the sts yaml files to control whether or not the `not
test_of_sts`/`not webidentity_test` attrs are added to the pytest
command line

Fixes: https://tracker.ceph.com/issues/61838
Signed-off-by: Casey Bodley <cbodley@redhat.com>