Code cleanup.

LDAPReplicationDomain.java:
Removed generator field, duplicated with super class.
Extracted method getFirstResult(InternalSearchOperation).
In findAndRenameChild(), removed useless null check.

PersistentServerState.java
Changed visibilities to default or private.
Removed conn field + used static import instead.
Removed on ctor only used by tests.
In save() simplified the code a lot.
In checkAndUpdateServerState(), reduced local variable scope + renamed a few of them.
Extracted method getFirstResult(InternalSearchOperation).

PersistentServerStateTest.java:
Consequence of removing one ctor from PersistentServerState.