[FFI] Fix dynamic FFI index to ensure compatibility (#17727)

This PR sets the dynamic index to the original value
in past versions so we can have stable compatibility
when we phase out static objects.

Author: tqchen

include/tvm/runtime/object.h

@@ -77,9 +77,12 @@ struct TypeIndex {
     /*! \brief runtime::RPCObjectRef */
     kRuntimeRPCObjectRef = 9,
     // static assignments that may subject to change.
-    kStaticIndexEnd,
-    /*! \brief Type index is allocated during runtime. */
-    kDynamic = kStaticIndexEnd
+    kStaticIndexEnd = 10,
+    /*!
+     * \brief Type index is allocated during runtime, keeping it as
+     * constant for now to ensure compatibility across versions
+     */
+    kDynamic = 12
   };
 };  // namespace TypeIndex