Issue #3548028: Show proper message when submission limit is reached.

Problem: The Webform message for ADMIN_CLOSED was misleading. It displayed "This webform is closed..." even when the submission limit was reached but the form was still open. Anonymous users only saw the warning "No more submissions are permitted" without proper context.

Solution:

• Added a new message constant ADMIN_LIMIT_REACHED in WebformMessageManagerInterface.
• Updated WebformMessageManager to return a clear, user-friendly message when submission limit is reached.
• Updated WebformSubmissionForm to use ADMIN_LIMIT_REACHED instead of ADMIN_CLOSED for total and user limit checks.
• Ensures admins and users see accurate information when limits are reached.

Testing:

1. Create a webform with a submission limit.
2. Submit once as a user.
3. Reload the form page:
   • Admin sees the proper info message.
   • Anonymous users see the warning indicating the submission limit has been reached.

Closes #3548028