Update persona-toolkit on DB servers to resolve DST UTC bug

[gene1wood]

Our version of percona-toolkit is affected by this bug

https://bugs.launchpad.net/percona-toolkit/+bug/1078416

Which causes this check

https://github.com/mozilla/identity-ops/blob/master/chef/cookbooks/persona-db/files/default/usr/local/nagios/libexec/check_mysql_percona_heartbeat

to trigger false positives for an hour when the time changes. We'll need to fix this prior to March 9th 2014

http://www.percona.com/doc/percona-toolkit/2.1/pt-heartbeat.html