Bug 13264: Follow up: in opac_utf8.t insert also delete of biblio

Bug 13264: Follow up: in opac_utf8.t insert also delete of biblio

In previous version of the test opac_utf8.t clears import from resevoir
but it doesn't delete record from biblio table in MySQL.
This the standard work of the feature, see:
http://manual.koha-community.org/3.18/en/catalogtools.html#managestaged

Now the script deletes also record on MySQL level.
No necessary on Zebra level because it uses a temporaney Zebra index that it is
clenaned at the end of the script.

Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>