Bug 18118: Unexpected behaviour with 'GoogleOpenIDConnect' and 'OpacPublic' syspref...

Bug 18118: Unexpected behaviour with 'GoogleOpenIDConnect' and 'OpacPublic' syspref combination.

TEST PLAN
----------
1/ configure a working 'GoogleOpenIDConnect' account

See comment #5 which also links back to
https://bugs.koha-community.org/bugzilla3/show_bug.cgi?id=16892#c3

2/ set 'OpacPublic' (under OPAC) to 'Disabled' and
   'GoogleOpenIDConnect' (under Administration) to 'Yes'.

3/ log in user successfully via google-auth, observe redirect to
   opac-user.pl (bad)

4/ apply patch
   -- on kohadevbox remember to restart all! Plack is unforgiving. :)

5/ log in user successfully via google-auth, observe expected
   redirect to opac-main.pl (good)

While I would normally suggest running koha qa test tools, because
this file doesn't end in .pl, it doesn't get picked up by them.

6/ perlcritic -4 opac/svc/auth/googleopenidconnect
   -- notice this is a level better than required. :)

This also eyeballs easily well.

Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>