[ty] Avoid overcounting shared memory usage (#19773)

## Summary

Use a global tracker to avoid double counting `Arc` instances.

crates/ty_python_semantic/src/suppression.rs

@@ -86,7 +86,7 @@ declare_lint! {
     }
 }
 
-#[salsa::tracked(returns(ref), heap_size=get_size2::heap_size)]
+#[salsa::tracked(returns(ref), heap_size=ruff_memory_usage::heap_size)]
 pub(crate) fn suppressions(db: &dyn Db, file: File) -> Suppressions {
     let parsed = parsed_module(db, file).load(db);
     let source = source_text(db, file);