Bug 20974: Remove files left behind after removing Solr

Bug 20974: Remove files left behind after removing Solr

Some files were left behind when Bug 12538 removed support for Solr.
This patch removes them.

To test, apply the patch and fail to observe the existence of these
files:

koha-tmpl/opac-tmpl/bootstrap/en/includes/search/facets.inc
koha-tmpl/opac-tmpl/bootstrap/en/includes/search/page-numbers.inc
koha-tmpl/opac-tmpl/bootstrap/en/includes/search/resort_form.inc

Perform a search in the OPAC to confirm that nothing broke.

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>