Do we still need to execute ScanVMSpecificRoots for sanity GC?

[qinsoon]

mmtk-core/src/util/sanity/sanity_checker.rs

Lines 81 to 82 in 3252c24

	scheduler.work_buckets[WorkBucketStage::Prepare]
	.add(ScanVMSpecificRoots::<SanityGCProcessEdges<P::VM>>::new());

For sanity GC, we should be caching all the roots from any root work packet created by RootsWorkFactory. Do we still need to run ScanVMSpecificRoots in sanity GC?