Auto merge of #139067 - m-ou-se:terminating-scopes-no-hashset, r=wesleywiser

Remove `terminating_scopes` hash set.

Instead of inserting and checking ids in a hashset, we can just pass a boolean as argument.

For example:

```diff
-    visitor.terminating_scopes.insert(arm.hir_id.local_id);
-    visitor.enter_node_scope_with_dtor(arm.hir_id.local_id);
+    visitor.enter_node_scope_with_dtor(arm.hir_id.local_id, true);
```

Author: bors