LP#1759343 Fix annotate payment setting name

LP#1759343 Fix annotate payment setting name

This setting was added to the database with the 'eg.' prefix, but in
the code it was not used.  The end effect was that the setting likely
worked, but was not saved in the way expected.

This makes the setting name in the code match the DB.

Signed-off-by: Dan Wells <dbw2@calvin.edu>
Signed-off-by: Chris Sharp <csharp@georgialibraries.org>