Change allocation strategy for zabbix-server

If user will use zabbix-server on node with more than one
hard disk, and ubuntu os, it will lead to errors on provsion
stage for the server

Mounting /var partition on ubuntu will lead to errors
cause there is no os volume group on ubuntu

- add /var/lib/mysql partition, will grow most of all,
  because zabbix is using mysql for storing stats
- change os vg to use min allocator

Change-Id: I2869a7ab341b7069a3b9d943cff9680ea5bf0439
Closes-Bug: 1341691
Merge "Change allocation strategy for zabbix-server"