SAK-25512 Don't require email address to be completed on sites.

This fixes the bug where the UI indicated that the email address on a site wasn't required but the code was insisting that users completed it. This was a change in behaviour from 2.8.x and 2.9.x

git-svn-id: https://source.sakaiproject.org/svn/site-manage/trunk@132973 66ffb92e-73f9-0310-93c1-f5514f145a0a