MT#9709 fix b196b6b04f Using wrong var.

This was producing empty values at ngcp-ossbss template mysql_values.cfg file
on a cluster_set of central type

Change-Id: I68160a9c5bef078d3154c6e8da6db1e9bcbb07aa
(cherry picked from commit 2437330d4e39a3904dbb1db426fca662daa0d502)