Bug 5904: make patron search autocompletion respect IndependentBranches

Bug 5904: make patron search autocompletion respect IndependentBranches

Test plan:
- Add a staff user foo in a library A
- Add a staff user bar in a library B
- log in as foo and try to search 'bar'
- Switch on (Prevent) the syspref IndependentBranches
- the search returns no result
- log in as a superlibrarian
- Check that you are allowed to search all patrons.

Signed-off-by: Srdjan <srdjan@catalyst.net.nz>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Passes koha-qa.pl, works as advertised.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>