Bug 24801: Display all the categories - Selenium fix

Bug 24801: Display all the categories - Selenium fix

To make sure we are going to be able to click on the "Delete" button of
our newly created category PATRON_CAT, we are displaying them all.

Test plan:
Create several patron categories that will fill the first page:

use t::lib::TestBuilder;
my $builder = t::lib::TestBuilder->new;
for my $i ( 1..20 ) {
    $builder->build_object({ class => 'Koha::Patron::Categories', value => { description => "cat_$i" } });
}

Execute the selenium tests.

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>