Modernize ActiveMQMessageAudit to be lock-free

[mattrpav]

The current ActiveMQMessageAudit is implemented using synchronized blocks around an LRUCache implemented with a LinkedHashMap as an extension to the sync-free ActiveMQMessageAuditNoSync class.

Modern Java language collection (ConcurrentHashMap) and lock-free programming approach can improve performance (especially when there are concurrent producers). Both classes can be replaced with a single, modern implementation.

A modernized MessageAudit:

• Provide exact same functional capabilities as current ActiveMQMessageAudit/ActiveMQMessageAuditNoSync
• Allow for shrinking/growing the audit size without completely clearing the list