Should remove and restore labeller only from workers

Currently in some tests we are waiting for
the node labeller to be resumed in any nodes
including unschedulable nodes and that will not work
because master shouldn't be labeled by node
labeller.

Signed-off-by: bmordeha <bmodeha@redhat.com>

tests/hyperv_test.go

@@ -1,7 +1,6 @@
 package tests_test
 
 import (
-	"context"
 	"fmt"
 	"strings"
 	"time"
@@ -125,21 +124,15 @@ var _ = Describe("[Serial][sig-compute] Hyper-V enlightenments", func() {
 
 			BeforeEach(func() {
 				if isTSCFrequencyExposed(virtClient) {
-					nodeList, err := virtClient.CoreV1().Nodes().List(context.Background(), metav1.ListOptions{})
-					Expect(err).ToNot(HaveOccurred())
-
-					for _, node := range nodeList.Items {
+					for _, node := range libnode.GetAllSchedulableNodes(virtClient).Items {
 						stopNodeLabeller(node.Name, virtClient)
 						removeTSCFrequencyFromNode(node)
 					}
 				}
 			})
 
 			AfterEach(func() {
-				nodeList, err := virtClient.CoreV1().Nodes().List(context.Background(), metav1.ListOptions{})
-				Expect(err).ToNot(HaveOccurred())
-
-				for _, node := range nodeList.Items {
+				for _, node := range libnode.GetAllSchedulableNodes(virtClient).Items {
 					_ = resumeNodeLabeller(node.Name, virtClient)
 				}
 			})