Revert specifying superuser by setting `SCYLLA_EXT_OPTS` (https://github.com/scylladb/python-driver/pull/759) once proper API is implemented in scylla-ccm - https://github.com/scylladb/scylla-ccm/issues/729.
Revert specifying superuser by setting
SCYLLA_EXT_OPTS(#759) once proper API is implemented in scylla-ccm - scylladb/scylla-ccm#729.