Allow users to bypass the registration flow

What does this MR do and why?

Users who are signing up to join their teams project should have the ability to skip the registration steps that involve creating a group and project.

• removes progress bar from registration flow as a side effect

part of: #340560

Screenshots or screen recordings

before	after

How to set up and validate locally

1. Enable the bypass_registration experiment

   Feature.enable(:bypass_registration)

2. Sign up via http://localhost:3000/users/sign_up

3. Confirm that selecting Join a project bypasses the rest of the registration flow, while Create a new project does not.

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.