src: remove dead comments about return_code_cache

This behavior of sometimes returning the function & other times
returning the code cache was removed a long time ago in the referenced
PR, as evinced by the return type `MaybeLocal<Function>`. Remove these
incorrect comments.

Refs: #24950
PR-URL: #47083
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>
Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com>
Reviewed-By: Chengzhong Wu <legendecas@gmail.com>

src/node_builtins.cc

@@ -256,9 +256,6 @@ bool BuiltinLoader::Add(const char* id, std::string_view utf8source) {
   return Add(id, UnionBytes(out));
 }
 
-// Returns Local<Function> of the compiled module if return_code_cache
-// is false (we are only compiling the function).
-// Otherwise return a Local<Object> containing the cache.
 MaybeLocal<Function> BuiltinLoader::LookupAndCompileInternal(
     Local<Context> context,
     const char* id,
@@ -356,9 +353,6 @@ MaybeLocal<Function> BuiltinLoader::LookupAndCompileInternal(
   return scope.Escape(fun);
 }
 
-// Returns Local<Function> of the compiled module if return_code_cache
-// is false (we are only compiling the function).
-// Otherwise return a Local<Object> containing the cache.
 MaybeLocal<Function> BuiltinLoader::LookupAndCompile(Local<Context> context,
                                                      const char* id,
                                                      Realm* optional_realm) {