Bug 24786: (QA follow-up) Do not use 'hidden' attribute
The hidden attribute for loading an element hidden is known to have
issues and inconsistencies accross browsers.
This patch instead updates the relevent input options to use an inline
style of 'display: none' to hide the elements on page load and then
.show, .hide for subsquent changes linked to the library branch picker
change.
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>