Also emit ICE dump files on stable

cf. <rust-lang#132245> where originally
we made it nightly-only in case there was some problems with the ICE
dumping infra breaking stable users. However, a good amount of time has
since passed and such bugs have not materialized. It was also waiting
for cargo gc work, but the timeline of that is unclear.

Also note that ICE dumping is already perma-unstable behavior, so if
this somehow is problematic it is very easy to revert.

compiler/rustc_driver_impl/src/lib.rs

@@ -1337,9 +1337,6 @@ fn ice_path_with_config(config: Option<&UnstableOptions>) -> &'static Option<Pat
     }
 
     ICE_PATH.get_or_init(|| {
-        if !rustc_feature::UnstableFeatures::from_environment(None).is_nightly_build() {
-            return None;
-        }
         let mut path = match std::env::var_os("RUSTC_ICE") {
             Some(s) => {
                 if s == "0" {