Fix hooks on 0.92.0 (#12383)

# Description
Fixes #12382, where overlay changes from hooks were not preserved into
the global state. This was due to creating child stacks for hooks, when
the global stack should have been used instead.

crates/nu-protocol/src/engine/stack.rs

@@ -125,9 +125,9 @@ impl Stack {
         unique_stack.env_vars = child.env_vars;
         unique_stack.env_hidden = child.env_hidden;
         unique_stack.active_overlays = child.active_overlays;
-        for item in child.parent_deletions.into_iter() {
-            unique_stack.vars.remove(item);
-        }
+        unique_stack
+            .vars
+            .retain(|(var, _)| !child.parent_deletions.contains(var));
         unique_stack
     }
     pub fn with_env(