Fetch {Cluster}Tasks using generated client

It seems like using the Lister to fetch ClusterTasks and Tasks results
in some flakiness when attempting to run the Task immediately after it's
created (as in clustertask.yaml). Using the Lister is likely faster, due
to caching, but if it means failed runs for just-created Tasks, that
speed isn't worth it.

pkg/reconciler/taskrun/taskrun.go

@@ -202,7 +202,7 @@ func (c *Reconciler) getTaskFunc(tr *v1alpha1.TaskRun) (resources.GetTask, v1alp
 	kind := v1alpha1.NamespacedTaskKind
 	if tr.Spec.TaskRef != nil && tr.Spec.TaskRef.Kind == v1alpha1.ClusterTaskKind {
 		gtFunc = func(name string) (v1alpha1.TaskInterface, error) {
-			t, err := c.clusterTaskLister.Get(name)
+			t, err := c.PipelineClientSet.TektonV1alpha1().ClusterTasks().Get(name, metav1.GetOptions{})
 			if err != nil {
 				return nil, err
 			}
@@ -211,7 +211,7 @@ func (c *Reconciler) getTaskFunc(tr *v1alpha1.TaskRun) (resources.GetTask, v1alp
 		kind = v1alpha1.ClusterTaskKind
 	} else {
 		gtFunc = func(name string) (v1alpha1.TaskInterface, error) {
-			t, err := c.taskLister.Tasks(tr.Namespace).Get(name)
+			t, err := c.PipelineClientSet.TektonV1alpha1().Tasks(tr.Namespace).Get(name, metav1.GetOptions{})
 			if err != nil {
 				return nil, err
 			}