Bug 31490: Terminology: change 'staff client' to 'staff interface' in marc-overlay...

Bug 31490: Terminology: change 'staff client' to 'staff interface' in marc-overlay-rule

This patch corrects the terminology for staff interface in the record overlay rules administration page.

To test:
1) Apply patch
2) Enable the MARCOverlayRules system preference
3) Go to Administration > Record overlay rules
4) Open the 'Filter' drop-down menu
=> The second option should read 'Staff interface MARC editor'

Signed-off-by: Michaela Sieber <michaela.sieber@kit.edu>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>