Bug 11912: (regression tests) GetMarcISBN wrongly prepends a space to ISBNs

Bug 11912: (regression tests) GetMarcISBN wrongly prepends a space to ISBNs

This patch makes the tests run in both MARC21 and UNIMARC contexts.
It previously run only for MARC21. It mocks what needs to be mocked.

To test, run
 - prove t/db_dependent/Biblio.t
=> Notice the first ISBN has a space in front of it and those tests fails.

Signed-off-by: Nicolas Legrand <nicolas.legrand@bulac.fr>
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>