Fix group work item "add todo" button

What does this MR do and why?

Fix group work item "add todo" button (#427797 (closed))

Group work item query asks for workItem.project.* but it is not at the project-level so it fails. We fix this by updating the query to workItem.namespace.*, but since workItem.namespace.archived doesn't exist then we update it to workItem.archived

This MR is part of adding work items at the group-level (#393240 (closed))

Behind feature flag namespace_level_work_items

Screenshots or screen recordings

Before	After
Screen_Recording_2023-10-19_at_2.36.31_pm	Screen_Recording_2023-10-19_at_2.36.47_pm

How to set up and validate locally

1. In rails console

   Feature.enable(:namespace_level_work_items)

2. Visit any work items list page for a paid subscription group such as http://127.0.0.1:3000/groups/flightjs/-/work_items
3. Create an epic
4. Click on created epic and confirm you can add/remove todos without errors

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #427797 (closed)