Bug 14350: Missing statement in kohastructure.sql - DROP TABLE IF EXISTS borrower_sync

Bug 14350: Missing statement in kohastructure.sql - DROP TABLE IF EXISTS borrower_sync

Reported by Jonathan on bug 11401:

DROP TABLE IF EXISTS borrower_sync;
is missing in installer/data/mysql/kohastructure.sql

To test:
- Run the web installer and confirm all tables are
  created correctly

Signed-off-by: Indranil Das Gupta (L2C2 Technologies) <indradg@gmail.com>
Signed-off-by: Jonathan Druart <jonathan.druart@koha-community.org>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>