settings: Improve wording in delete user group confirmation modal.

Fixes #22593.

static/js/settings_user_groups.js

@@ -396,8 +396,10 @@ export function set_up() {
             group_name: user_group.name,
         });
 
+        const user_group_name = user_group.name;
+
         confirm_dialog.launch({
-            html_heading: $t_html({defaultMessage: "Delete user group"}),
+            html_heading: $t_html({defaultMessage: "Delete {user_group_name}?"}, {user_group_name}),
             html_body,
             on_click: delete_user_group,
         });

static/templates/confirm_dialog/confirm_delete_user.hbs

@@ -1,5 +1,5 @@
 <p>
     {{#tr}}
-    Are you sure you want to delete <b>{group_name}</b>?
+    This action cannot be undone.
     {{/tr}}
 </p>