fix(config_setup): clean old encrypt_conf
fix(config_setup): clean old encrypt_conf

In some nemesis, node.config_setup() is called for updating the
node configuration (prepare config files and update scylla.yaml).
Some configuration has been done in cluster init.

In restart_with_resharding nemesis:
|
|  Command: 'sudo mv /tmp/encrypt_conf /etc/'
|  Exit code: 1
|
|  Stderr:
|  mv: cannot move ‘/tmp/encrypt_conf’ to ‘/etc/encrypt_conf’: File exists

Signed-off-by: Amos Kong <eb01d8f828a6c9a20be4534e72e049aaf41503df@scylladb.com>

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