QPID-4555: HA Replace QueueSettings::declaredExclusive with isTemporary.

Minor reorganization to make things clearer. It was not at all obvious what
declaredExclusive mean, isTemporary makes more sense (suggested by gsim
https://reviews.apache.org/r/9258/)

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1444200 13f79535-47bb-0310-9956-ffa450edef68