SOLR-5473 use zk.clean() instead of zk.delete()
SOLR-5473 use zk.clean() instead of zk.delete()

git-svn-id: 308d55f399f3bd9aa0560a10e81a003040006c48@1626131 13f79535-47bb-0310-9956-ffa450edef68

cscorley/solr-only-mirror,cscorley/solr-only-mirror,cscorley/solr-only-mirror