varnishkafka: do not reload on every puppet run

Because of how the notify event propagation works in puppet, the use of
notify => refreshonly => notify chains doesn't work, and results in
executing a ganglia restart on every puppet run

Change-Id: I85380223e698f10d6b48fa636876498b013d6b8b
Signed-off-by: Giuseppe Lavagetto <glavagetto@wikimedia.org>