Bug 17222: Remove use of onclick from OPAC member entry page

Bug 17222: Remove use of onclick from OPAC member entry page

There is only one instance on onclick here, and that is the clear date
function.

To test, make sure clicking 'Clear date' next to Date of Birth works the
same before and after the patch.

Sponsored-by: Catalyst IT
Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
(cherry picked from commit 167be41dcc42f8456a69700475eb927593f78fb2)
Signed-off-by: Frédéric Demians <f.demians@tamil.fr>