Fixes 'Zone is empty' errors in PD upgrade tests; skips pd tests with inline volume in multizone clusters

test/e2e/framework/util.go

@@ -348,6 +348,16 @@ func SkipUnlessMultizone(c clientset.Interface) {
 	}
 }
 
+func SkipIfMultizone(c clientset.Interface) {
+	zones, err := GetClusterZones(c)
+	if err != nil {
+		Skipf("Error listing cluster zones")
+	}
+	if zones.Len() > 1 {
+		Skipf("Requires more than one zone")
+	}
+}
+
 func SkipUnlessClusterMonitoringModeIs(supportedMonitoring ...string) {
 	if !ClusterMonitoringModeIs(supportedMonitoring...) {
 		Skipf("Only next monitoring modes are supported %v (not %s)", supportedMonitoring, TestContext.ClusterMonitoringMode)