Remove all references to the deprecated HubSize feature flag from the ACM and MCE codebase, as it is no longer being pursued in ACM 2.15. This ensures the codebase remains clean and up to date.

-------------------------------------------------------------------------------------------------------
QE Hand Off Template (fill out when moving to Review) 10/6/25:

Summary of the Work:
What was implemented or fixed? Include a brief description of the problem (if applicable) and how it was addressed.
e.g., "Updated the UI to show validation errors for the form. The previous implementation did not surface backend validation issues."

Key Areas to Verify:

1. What functionality should QE focus on? List what was tested or what is most important to validate.
2. Ensure the new validation messages appear for required fields
3. Confirm the workflow still completes as expected after validation fixes
4. Any edge cases or high-risk areas touched by the change

Fix or Feature Availability:
When will this be available in a build?
Code merged on: YYYY-MM-DD
Expected downstream build tag (if known): example-build-tag
(Optional) Related PR(s): Link