OAK-1892 - OrderedIndexConcurrentClusterIT takes too long

Merging r1607362 and r1610634 into 1.0 branch



git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/branches/1.0@1610939 13f79535-47bb-0310-9956-ffa450edef68