[Enhancement] Optimize memory usage

[Colvin-Y]

Is your feature request related to a problem? Please describe.
Descheduler use too many memory when runs in dry-run mode. In dry-run mode, we perform a full copy of the in-memory data, which results in its memory usage being twice that of the scheduler within the cluster. This is very resource-intensive in large-scale scenarios.

	if d.rs.DryRun {
		klog.V(3).Infof("Building a cached client from the cluster for the dry run")
		// Create a new cache so we start from scratch without any leftovers
		fakeClient := fakeclientset.NewSimpleClientset()
		// simulate a pod eviction by deleting a pod
		fakeClient.PrependReactor("create", "pods", d.podEvictionReactionFnc(fakeClient))
		fakeSharedInformerFactory := informers.NewSharedInformerFactory(fakeClient, 0)

		err := d.ir.CopyTo(fakeClient, fakeSharedInformerFactory)
		if err != nil {
			return err
		}

Describe the solution you'd like
Only retain the necessary fields in the cache, removing unnecessary information to optimize memory usage.