Bug 23042: Only include GET params in return URL for Shibboleth

Bug 23042: Only include GET params in return URL for Shibboleth

The shibboleth return target included POST parameters in the URL string,
this meant that a failed local login POST would include the username and
password used in the attemtped login in plaintext in the redirect URL
that is appended to the shibboleth login URL.

Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>