Bug 38200: Remove dead code to delete authorities in authorities/authorities.pl

Bug 38200: Remove dead code to delete authorities in authorities/authorities.pl

It has probably never been used. There's no sign of any UI to delete from
the authority editor or auth_finder in the last 13 years of templates, and
it was unused when it landed; the patch that actually made the first patch
work, a month later, put deleting authorities in authorities_home.pl, where
it has been ever since.

It certainly hasn't been used since bug 17600 landed in 2021, since it
doesn't 'use C4::AuthoritiesMarc qw( DelAuthority );' and so if you try to
use it you just get an error for your trouble.

Sponsored-by: Chetco Community Public Library
Signed-off-by: Yanjun Li <yanjun.li@bywatersolutions.com>
Amended-by: Jonathan Druart
tidy

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>