T2958: Fix path for leases to config directory

The leases path should be in /config directory to save leases
between reboots.
The typo was in this commit c07055258b853de641d2a1353582800b24c514d2
Before this the idea was to get leases from /run directory only
for livecd images. But then we added /config directory for livecd.
PR was modified and incorrect variable directory /run was used.
Fix it.