Bug 15325: Fix --table option of rebuild_zebra.pl

Bug 15325: Fix --table option of rebuild_zebra.pl

Option's value given on command line was never used and 'biblioitems'
was used instead.

Test plan:
1. git checkout master
2. perl misc/migration_tools/rebuild_zebra.pl -b -t items --where "price = 42"
3. You should see errors printed on screen about an unknown column
4. Apply patch
5. perl misc/migration_tools/rebuild_zebra.pl -b -t items --where "price = 42"
6. No errors \o/

Signed-off-by: Frédéric Demians <f.demians@tamil.fr>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>