Removes the com_admin.profile which no longer exists in j4
Adds the php extension simplexml as a hard dependency in composer (as without it none of our forms will work and my IDE moans at me whenever I look at any Form related class
Fixes the group that is passed into the validate function
To test edit your user in the backend and hit save. Before patch it fails. After patch it works. Note there are various bugs related to the showon not working there and language strings not loaded (that's covered by #17444). I'm calling that out of scope for this PR.