Bug 32426: Changes for opac-memberentry

Bug 32426: Changes for opac-memberentry

Test plan:
Enable self registration, pick a default category too for it.
The changes will be tested later with a plugin, but now change
Koha/Patron.pm as follows:
 sub _generate_userid_legacy { # as we always did
     my ($self) = @_;
+return $self;
So, add the return $self line only.
Restart all. Try to register an account on OPAC.
You should see an alert about problems processing your registration.
Undo the change in Patron.pm and restart all.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>