improvement(ssh-transport): enabling libssh2 by default
improvement(ssh-transport): enabling libssh2 by default

following -1 exit code issues
https://github.com/scylladb/scylla-cluster-tests/issues/4301

scylladb/scylla-cluster-tests,scylladb/scylla-cluster-tests,scylladb/scylla-cluster-tests,scylladb/scylla-cluster-tests,scylladb/scylla-cluster-tests