Revert "MessageQueue: track tail of queue"

Revert submission 25706335-message_queue_tail_tracking

Reason for revert: <Test Revert b/318606175>

Reverted changes: /q/submissionid:25706335-message_queue_tail_tracking

Change-Id: I43587cd8ee18b044c358404b27d6ce1967402ed9
1 file changed