Pass test ctx to taskrun reconciler instead of background ctx

Prior to this commit the test reconciler was being passed a background
context to its Reconciler method in TestReconcileValidDefaultWorkspace.

This commit passes the test assets context instead which will hopefully
be immediately up-to-date with configmap changes like the Default
TaskRun Workspace Binding config.

Author: Scott

pkg/reconciler/taskrun/taskrun_test.go

@@ -2566,7 +2566,7 @@ func TestReconcileValidDefaultWorkspace(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	if err := testAssets.Controller.Reconciler.Reconcile(context.Background(), getRunName(taskRun)); err != nil {
+	if err := testAssets.Controller.Reconciler.Reconcile(testAssets.Ctx, getRunName(taskRun)); err != nil {
 		t.Errorf("Expected no error reconciling valid TaskRun but got %v", err)
 	}