Bug 21450: Cache authorities search using term and auth_type

Bug 21450: Cache authorities search using term and auth_type

This is a simple fix to prevent incorrect caching of results when using
link_bibs_to_authorities

To test:
1 - Find or create a record with the same term in a subject and genre
heading
2 - Find or create authority records for the term as a subject and genre
type
3 - Run link bibs to authorities
4 - Verify both tags in the record are linked to the subject heading
5 - Aply patch
6 - Unlink the record and re-run the script (or just re-run)
7 - Each tag should be linked to correct authority

Signed-off-by: Frank Hansen <frank.hansen@ub.lu.se>
Signed-off-by: Liz Rea <wizzyrea@gmail.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>