QPID-6169: [Java Broker] HA Prevent IllegalStateException possibility from remote state learner

* Prevents a race condition between a node becoming master and the desired durability being read from
 store and set on the environment.

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1633181 13f79535-47bb-0310-9956-ffa450edef68