Scheduler should use shared informer for pods

Previously, the scheduler created two separate list watchers. This
changes the scheduler to be able to leverage a shared informer, whether
passed in externally or spawned using the new in place method. This
removes the last use of a "special" informer in the codebase.

Allows someone wrapping the scheduler to use a shared informer if they
have more information avaliable.

plugin/pkg/scheduler/algorithmprovider/defaults/compatibility_test.go

@@ -352,6 +352,7 @@ func TestCompatibility_v1_Scheduler(t *testing.T) {
 			"some-scheduler-name",
 			client,
 			informerFactory.Core().V1().Nodes(),
+			informerFactory.Core().V1().Pods(),
 			informerFactory.Core().V1().PersistentVolumes(),
 			informerFactory.Core().V1().PersistentVolumeClaims(),
 			informerFactory.Core().V1().ReplicationControllers(),