Bug 15168: Remove C4:Serials::ItemizeSerials

Bug 15168: Remove C4:Serials::ItemizeSerials

This subroutine has been introduced in 2006, when C4::Serials has been
added to the codebase.
If you checkout this commit
commit 18d2cd099085e443d713a1546e029faa81481814
Date:   Fri Jul 7 08:45:47 2006 +0000
    this file replace C4/Bull.pm

You won't find any occurrences of this subroutine neither.

Interesting module's name by the way.

Test plan:
  git grep ItemizeSerials
should not return any result

Followed test plan, no results found.
Signed-off-by: Marc Véron <veron@veron.ch>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>