Flip USE_REGISTER_V2 to true.

[jwag956]

This continues the registration form migration to the new RegistrationV2 and deprecating the old RegisterForm and ConfirmRegisterForm.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.52%. Comparing base (7a515d0) to head (73c8246).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1112   +/-   ##
=======================================
  Coverage   98.52%   98.52%           
=======================================
  Files          40       40           
  Lines        5012     5014    +2     
=======================================
+ Hits         4938     4940    +2     
  Misses         74       74           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.