Remove an Arc holding module code from InstanceHandle (#2374)

We've generally moved to a model where `InstanceHandle` doesn't hold
ownership of its internals, instead relying on the caller to manage
that. This removes an allocation on the `Func::wrap` path but otherwise
shouldn't have much impact.

crates/jit/src/instantiate.rs

@@ -246,7 +246,6 @@ impl CompiledModule {
     ) -> Result<InstanceHandle, InstantiationError> {
         InstanceHandle::new(
             self.module.clone(),
-            self.code.clone(),
             &self.finished_functions.0,
             imports,
             mem_creator,