fix(system_auth and ldap): possible race condition
fix(system_auth and ldap): possible race condition

because the change in system_auth was the very first
thing running after configuring LDAP and changing SCT
to use LDAP users, it possible was not yet sync'ed on
all nodes, making nodetool commands to fail.
I think this change will resolve this small issue.

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