Bug 30294: Rename Koha::Recall->* used relationship names

Bug 30294: Rename Koha::Recall->* used relationship names

This patch renames the underlaying relationship names used in the
'patron' and 'library' subs so they are more clearly prefetchable and
also enabling them to be embeddable and searchable through an eventual
API route for recalls.

To test:
1. Apply the patch
2. Run:
   $ kshell
  k$ prove t/db_dependent/Koha/Recall*
=> SUCCESS: Tests pass, nothing really changes
3. Sign off :-D

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>