In Improve "Change Username" Account Settings #94640, we are introducing several tweaks to the Change Username feature to simplify the interfaces.

There's one change we've decided to address in a separate PR related to the "Create a matching site" feature. Whenever a user changes their username, we give them the option to create a blog that matches their new username. The interface for this currently consists of a couple of radio buttons, which are not selected by default:

The user can proceed without making any selection, resulting in only a username change with no site created. This UI is somewhat complex for its purpose, so I'd like to propose using a toggle instead:

Figma file: https://www.figma.com/design/wCm5Tzb7JBaG4WNowWbjES/Logical-Flows?node-id=5250-13523