agent: write latest profile change to default setting (#30408)

Reverts back to previous behavior where we update your settings so we
can load a new thread from your last configuration.

Release Notes:

- agent: Persist profile changes for new threads

crates/agent/src/message_editor.rs

@@ -200,7 +200,13 @@ impl MessageEditor {
         });
 
         let profile_selector = cx.new(|cx| {
-            ProfileSelector::new(thread.clone(), thread_store, editor.focus_handle(cx), cx)
+            ProfileSelector::new(
+                fs,
+                thread.clone(),
+                thread_store,
+                editor.focus_handle(cx),
+                cx,
+            )
         });
 
         Self {