[nfc][dfsan] Remove obsolete comment

GitOrigin-RevId: b6169e231e2c6880578f418ea630ced395ffbebb
diff --git a/test/dfsan/release_shadow_space.c b/test/dfsan/release_shadow_space.c
index 4cd770d..50cd67b 100644
--- a/test/dfsan/release_shadow_space.c
+++ b/test/dfsan/release_shadow_space.c
@@ -88,7 +88,6 @@
          before + mmap_cost_kb + mmap_shadow_cost_kb + mmap_origin_cost_kb);
 
 #ifdef ORIGIN_TRACKING
-  // Origin chain (sanitizer PersistentAllocator, never freed).
   // This value is chosen based on observed difference.
   const size_t mmap_origin_chain_kb = 4000;
 #else