Remove Arcs from QE (#5548)

## Description
This was added as an optimization in #5472. However, it seems to be the
cause of a transient bug that is causing the language server to crash
outlined in #5531.

We should revert this optimization until we understand how to avoid this
crash from happening. cc @tritao

## Checklist

- [x] I have linked to any relevant issues.
- [ ] I have commented my code, particularly in hard-to-understand
areas.
- [ ] I have updated the documentation where relevant (API docs, the
reference, and the Sway book).
- [ ] I have added tests that prove my fix is effective or that my
feature works.
- [ ] I have added (or requested a maintainer to add) the necessary
`Breaking*` or `New Feature` labels where relevant.
- [ ] I have done my best to ensure that my PR adheres to [the Fuel Labs
Code Review
Standards](https://github.com/FuelLabs/rfcs/blob/master/text/code-standards/external-contributors.md).
- [ ] I have requested a review from the relevant team or maintainers.

sway-core/src/query_engine/mod.rs

@@ -47,15 +47,15 @@ pub type ProgramsCacheMap = HashMap<ModulePath, ProgramsCacheEntry>;
 
 #[derive(Debug, Default)]
 pub struct QueryEngine {
-    parse_module_cache: Arc<RwLock<ModuleCacheMap>>,
-    programs_cache: Arc<RwLock<ProgramsCacheMap>>,
+    parse_module_cache: RwLock<ModuleCacheMap>,
+    programs_cache: RwLock<ProgramsCacheMap>,
 }
 
 impl Clone for QueryEngine {
     fn clone(&self) -> Self {
         Self {
-            parse_module_cache: self.parse_module_cache.clone(),
-            programs_cache: self.programs_cache.clone(),
+            parse_module_cache: RwLock::new(self.parse_module_cache.read().unwrap().clone()),
+            programs_cache: RwLock::new(self.programs_cache.read().unwrap().clone()),
         }
     }
 }