[cxx-interop] Update the C++ stdlib module name in SIL/verify_all_overlays.py

Author: egorzhdan

validation-test/SIL/verify_all_overlays.py

@@ -25,7 +25,7 @@
         continue
     # Skip the C++ standard library overlay because it's not yet shipped
     # in any released SDK.
-    if module_name == "std":
+    if module_name == "CxxStdlib":
         continue
     # TODO(TF-1229): Fix the "_Differentiation" module.
     if module_name == "_Differentiation":