Additional fixes OPENDJ-1247: Client side timeouts do not cancel bind or startTLS requests properly

* fix unit tests
* revert functionality which was abandoning expired requests as it introduces a potential, albeit very unlikely, race condition
* fix a bug which meant that the timeout checker could fail to enforce timeouts for the first LDAP connection
* minor improvements: only register connections which have a non-zero timeout; remove duplicate requestID field from LDAP future implementation.