Bug 34005: Move button toggling code outside JS for loop

Bug 34005: Move button toggling code outside JS for loop

When OpacHighlightedWords is set to "Highlight", if you search
in the OPAC and the number of keywords is odd (1, 3, 5, etc.),
then the "Unhighlight" / "Highlight" button will stop working
after a couple of clicks. The relevant commit is 9cb89b46397
from v20.11.00, where the code responsible for toggling the
"Unhighlight" / "Highlight" button was moved inside the JS
for loop that cycles through each term in the array of search
terms. This explains why the toggling only works when an even
number of search terms is being used.

This patch fixes that, by placing the button toggling code in
its original position (outside the JavaScript for loop of the
highlightOn() function).

Test plan:

0) If required, set OpacHighlightedWords to "Highlight".

1) Search for "history" in the OPAC, and view the details page
   of one of the results. Click on the "Unhighlight" button a
   few times -- after a couple of clicks the button text will
   stop toggling and you won't be able to remove the keyword
   highlight any more.

2) Apply this patch.

3) Repeat step 1): this time you should be able to toggle the
   search keyword highlighting no matter how many times you
   click on the "Unhighlight" / "Highlight" button.

4) Repeat step 1), but this time search for "century history":
   you should be able to toggle search keyword highlighting in
   the details page on and off repeatedly without any problems.

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>