It was not enabled due to some cqlsh dependency missing.
After 3 years it's hard to say if the thing is fixed or not,
but anyway we don't need another big dependecy while we already
have python driver used exstensively in tests. We use simple
wrapper file exec_cql.py, shared with auth_conns workload to
conveniently read needed preparation statements from the file.
Additionally we switch tablets off as counters don't support
it yet.