Bug 10686: Remove fields from searches for highlighting

If you do a fielded search like au:smith, "Smith" will not get
highlighted on the results page because the Javascript is looking for
the exact string "au:smith."

To test:
1) Turn on OpacHighlightedWords.
2) Do a simple keyword search.
3) Confirm that the word is highlighted on the results and details page.
4) Do a fielded search by entering au:smith (or whatever).
5) Confirm that the word is highlighted on the results and details page.
6) Sign off.

Signed-off-by: Mirko Tietgen <mirko@abunchofthings.net>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Passes koha-qa.pl, works as advertised.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>
(cherry picked from commit b0ea3be36c8e7ae6dc6f28820b1c26fc909d9039)
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>