This is a speculative fix as the problem is observed only on CI.
When run_async is called right after driver_connect and get_cql
it fails with ConnectionException('Host has been marked down or
removed').
If the approach proves to be succesfull we can start to deprecate
base get_cql in favor of get_ready_cql. It's better to have robust
testing helper libraries than try to take care of it in every test
case separately.
Fixes#17713Closesscylladb/scylladb#17772
7b60752e47