Enable OOM killing for etcd-events

Enable OOM killing like docker run etcd

roles/etcd/templates/etcd-events.j2

@@ -9,7 +9,6 @@
   {% if etcd_memory_limit is defined %}
   --memory={{ etcd_memory_limit|regex_replace('Mi', 'M') }} \
   {% endif %}
-  --oom-kill-disable \
   {% if etcd_cpu_limit is defined %}
   --cpu-shares={{ etcd_cpu_limit|regex_replace('m', '') }} \
   {% endif %}