cluster: rework env output to qualify zones using the region

Signed-off-by: Alejandro Mery <amery@jpi.io>

pkg/cluster/env.go

@@ -217,6 +217,13 @@ func genEnvZoneNodes(z *Zone) string {
 	return ""
 }
 
+func genEnvZoneRegion(z *Zone) string {
+	if z != nil && z.region != nil {
+		return z.region.Name
+	}
+	return ""
+}
+
 func genEnvZoneCephMonNames(m Machines) string {
 	var buf strings.Builder
 	m.ForEachMachine(func(p *Machine) bool {