Bug 10580: adjust Makefile.PL to reflect that Zebra no longer optional in Koha setup

Running Makefile.PL asks the user whether to install the Zebra
configuration files and different texts relate to the user having
chosen to use Zebra.

This patch removes references to choosing to use Zebra and removes
the related variables from the code.

To test:
- Apply the patch
- Go through the different install modes
- Verify that nothing nothing is broken

Sponsored-by: Universidad Nacional de Cordoba
Signed-off-by: Chris Cormack <chris@bigballofwax.co.nz>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>
(cherry picked from commit 0b989fe0b2097d747da1fd6d04aa8aecc5652d06)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>
Bug 10580: (follow-up) tweak wording about looking for zebrasrv & zebraidx

Signed-off-by: Galen Charlton <gmc@esilibrary.com>
(cherry picked from commit 1d276d58099fa60666bccc13c7b9d839946946c1)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>
Bug 11799: Housekeeping: Remove _biblionumber_sth from VirtualShelves.pm

This routine is no longer used.

Test plan:
Do a grep on the name.
(Bonus points:) Verify if you can perform some actions on lists.

No more occurences of _biblionumber_sth found
Signed-off-by: Marc Véron <veron@veron.ch>

Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>
(cherry picked from commit 5e0d450875f24d1f9ef6620b033b5179633589da)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>