Bug 33054: Fix unit tests

Bug 33054: Fix unit tests

This patch fixes the tests by making sure:
- The branch in userenv matches the home/holding branch so there are no
  circ rules getting in the middle
- Gives the user superlibrarian permissions for the same reasons above.

To test:
1. Run:
   $ ktd --shell
  k$ for i in $(seq 1 20 ); do prove t/db_dependent/Koha/Acquisition/Order.t ; done
=> FAIL: Notice it fails quite often. You can ctrl+c to interrupt once
it has failed at least once.
2. Apply this patch
3. Repeat 1
=> SUCCESS: it doesn't fail a single time
4. Sign off :-D

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>