Eliminate use of `extract()` in `validate_another_blog_signup()`. 

The extracted variables set/overwrite globals. `$user` does not need to be pulled from `validate_blog_form()` as it is not used in this function.

See #22400.


git-svn-id: https://develop.svn.wordpress.org/trunk@28445 602fd350-edb4-49c9-b593-d223f7449a82
Eliminate use of `extract()` in `validate_user_signup()`. 

`$orig_username` does not need to be pulled from `validate_user_form()` as it is not used in this function.

See #22400.


git-svn-id: https://develop.svn.wordpress.org/trunk@28446 602fd350-edb4-49c9-b593-d223f7449a82