Remove unnecessary Title Proper (Browse) index from config.metabib_field

As pointed out by Ben Shum and Dan Wells, we don't need this index, and
it made it only into the seed data and not into any upgrade script in
master.  It's a relic of bib-and-auth-browse development that ought to
have been removed before the merge to master.

Signed-off-by: Lebbeous Fogle-Weekley <lebbeous@esilibrary.com>
Signed-off-by: Dan Wells <dbw2@calvin.edu>