Bug 33237: (QA follow-up) Clarify tests and Mock

Bug 33237: (QA follow-up) Clarify tests and Mock

This patch tries to clarify the tests a little and expand their
coverage whilst also adding some defualt translated includes to the test
area and mocking the config to allow the tests to run without installing
translations.

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>
(cherry picked from commit a773770f738fe1b23d6c5b7cbafade636000374f)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>