Bug 18551: followup - hide advanced filters in header, move hidding to css file

Bug 18551: followup - hide advanced filters in header, move hidding to css file

Test plan:
The same as first patch, but also with advanced search form in header hidden
on page load - see comment 4

Issue with advanced search form is gone.
Signed-off-by: Marc Véron <veron@veron.ch>
Signed-off-by: Philippe <philippe.audet-fortin@inlibro.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>