Bug 34558: Update custom.sql for it-IT webinstaller

Bug 34558: Update custom.sql for it-IT webinstaller

It is an update of this file, here there are the specific customization for
italian users. There are simple changes on defaults values.

To test it:
1 - Start a web installation with italian language.
2 - Select Marc21 as biblio format
3 - Select all optional .sql files
4 - Conclude the installation.
5 - Go to MySQL command line and do:
    SELET value FROM systempreferences where variable = 'BorrowersTitles'
    You see: 'Sig|Sig.ra|Sig.na'
6 - Apply the patch.
7 - Drop and recreate the mysql db
8 - Redone the installation with italian language.
9 - Use the same options written above.
10 - Conclude the installation.
11 - Go to MySQL command line and do:
    SELECT value FROM systempreferences where variable = 'BorrowersTitles'
    You see: 'Sig|Sig.ra|Dott.|Dott.ssa'
12 - Refactor is OK

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
(cherry picked from commit 070af9aaf38e36c2c69d825ac43d28e288d62f04)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>