Do not build Rust code from GN, which needs the Chromium Rust toolchain.
Temporal is still enabled: its C++ headers and symbols come from the
temporal_capi crate that cargo already builds and links for the v8 crate.

--- cargo-crates/v8-150.4.0/.gn.orig	2006-07-24 01:21:28 UTC
+++ cargo-crates/v8-150.4.0/.gn
@@ -85,8 +85,6 @@ default_args = {
   # TODO: third_party/compiler-rt missing?
   use_llvm_libatomic = false
 
-  enable_rust = true
-  enable_rust_cxx = true
   v8_enable_temporal_support = true
 
   # prevent hashdos