Fix nil pointer issue when clusterset is deleted in leader

When the ClusterSet is deleted in leader Namespace, there will be
a nil pointer issue due to data inconsistent. This issue will cause
leader controller crash and restart. Refined codes to make data
consistent.
```
leader_clusterset_controller.go:72] "Received ClusterSet delete" config=""
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x18 pc=0x188b9b1]

goroutine 274 [running]:
antrea.io/antrea/multicluster/controllers/multicluster.(*MemberClusterAnnounceReconciler).processMCSStatus(0xc00052ff20)
	/antrea/multicluster/controllers/multicluster/memberclusterannounce_controller.go:181 +0x331
...
```

Signed-off-by: Lan Luo <luola@vmware.com>

multicluster/controllers/multicluster/leader_clusterset_controller.go

@@ -70,7 +70,9 @@ func (r *LeaderClusterSetReconciler) Reconcile(ctx context.Context, req ctrl.Req
 			return ctrl.Result{}, err
 		}
 		klog.InfoS("Received ClusterSet delete", "clusterset", klog.KObj(clusterSet))
-		r.StatusManager.CleanupMembers()
+		for _, removedMember := range r.clusterSetConfig.Spec.Members {
+			r.StatusManager.RemoveMember(common.ClusterID(removedMember.ClusterID))
+		}
 		r.clusterSetConfig = nil
 		r.clusterID = common.InvalidClusterID
 		r.clusterSetID = common.InvalidClusterSetID

multicluster/controllers/multicluster/leader_clusterset_controller_test.go

@@ -164,7 +164,8 @@ func TestLeaderClusterSetDelete(t *testing.T) {
 	err = fakeRemoteClient.Delete(context.TODO(), clusterSet)
 	assert.Equal(t, nil, err)
 
-	mockStatusManager.EXPECT().CleanupMembers()
+	mockStatusManager.EXPECT().RemoveMember(common.ClusterID("east"))
+	mockStatusManager.EXPECT().RemoveMember(common.ClusterID("west"))
 
 	req := ctrl.Request{
 		NamespacedName: types.NamespacedName{

multicluster/controllers/multicluster/memberclusterannounce_controller.go

@@ -74,7 +74,6 @@ type MemberClusterAnnounceReconciler struct {
 type MemberClusterStatusManager interface {
 	AddMember(memberID common.ClusterID)
 	RemoveMember(memberID common.ClusterID)
-	CleanupMembers()
 
 	GetMemberClusterStatuses() []multiclusterv1alpha1.ClusterStatus
 }
@@ -261,31 +260,16 @@ func (r *MemberClusterAnnounceReconciler) AddMember(memberID common.ClusterID) {
 		Conditions: conditions}
 
 	r.timerData[memberID] = &timerData{connected: false, lastUpdateTime: time.Time{}}
-	klog.InfoS("new member is added", "member", memberID)
+	klog.InfoS("Added member", "member", memberID)
 }
 
 func (r *MemberClusterAnnounceReconciler) RemoveMember(memberID common.ClusterID) {
 	r.mapLock.Lock()
 	defer r.mapLock.Unlock()
 
-	if _, ok := r.memberStatus[memberID]; ok {
-		delete(r.memberStatus, memberID)
-		return
-	}
-
-	if _, ok := r.timerData[memberID]; ok {
-		klog.InfoS("remove members", "member", memberID)
-		delete(r.timerData, memberID)
-		return
-	}
-}
-
-func (r *MemberClusterAnnounceReconciler) CleanupMembers() {
-	r.mapLock.Lock()
-	defer r.mapLock.Unlock()
-
-	r.memberStatus = make(map[common.ClusterID]*multiclusterv1alpha1.ClusterStatus)
-	r.timerData = make(map[common.ClusterID]*timerData)
+	delete(r.memberStatus, memberID)
+	delete(r.timerData, memberID)
+	klog.InfoS("Removed member", "member", memberID)
 }
 
 func (r *MemberClusterAnnounceReconciler) GetMemberClusterStatuses() []multiclusterv1alpha1.ClusterStatus {

multicluster/controllers/multicluster/memberclusterannounce_controller_test.go

@@ -114,12 +114,24 @@ func TestStatusAfterAdd(t *testing.T) {
 		},
 	}
 
-	//[]multiclusterv1alpha1.ClusterStatus
 	status := memberClusterAnnounceReconcilerUnderTest.GetMemberClusterStatuses()
+	expectedTimeData := memberClusterAnnounceReconcilerUnderTest.timerData
 	assert.Equal(t, 1, len(status))
+	assert.Equal(t, 1, len(expectedTimeData))
 	verifyStatus(t, expectedStatus, status[0])
 }
 
+func TestStatusAfterDelete(t *testing.T) {
+	setup()
+	memberClusterAnnounceReconcilerUnderTest.AddMember("east")
+	memberClusterAnnounceReconcilerUnderTest.RemoveMember("east")
+
+	status := memberClusterAnnounceReconcilerUnderTest.GetMemberClusterStatuses()
+	expectedTimeData := memberClusterAnnounceReconcilerUnderTest.timerData
+	assert.Equal(t, 0, len(status))
+	assert.Equal(t, 0, len(expectedTimeData))
+}
+
 func TestStatusAfterReconcile(t *testing.T) {
 	TestStatusAfterAdd(t)