Remove 'keepstats' queue option from sample config, as it's no longer used.

https://reviewboard.asterisk.org/r/115/

(closes issue #15820)
Reported by: kshumard


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@222548 65c4cc65-6c06-0410-ace0-fbb531ad65f3

configs/queues.conf.sample

@@ -9,11 +9,6 @@
 ;
 persistentmembers = yes
 ;
-; Keep Stats
-;    Keep queue statistics during a reload. Default is 'no'
-;
-keepstats = no
-;
 ; AutoFill Behavior
 ;    The old/current behavior of the queue has a serial type behavior
 ;    in that the queue will make all waiting callers wait in the queue