[cinder] update the max_over_subscription_ratio to 1.5
[cinder] update the max_over_subscription_ratio to 1.5

After discussions of the current status in eu-de-1, we
agreed to update the max_over_subscription_ratio to 1.5
to limit the already overcommited netapp.

sapcc/helm-charts,sapcc/helm-charts,sapcc/helm-charts,sapcc/helm-charts