Bug 29481: Terminology: Collection code, call number

Bug 29481: Terminology: Collection code, call number

This patch corrects an instance of the phrase "Collection code,"
replacing it with the standard "Collection."

To test, apply the patch and restart services.

- In the staff interface, go to Administration -> System preferences and
  set the OpacItemLocation preference to "library, collection code, and
  call number."
- In the OPAC, search the catalog using a term which will return
  multiple results.
- In the search results, item descriptions in the "Availability" line
  should read like this:

  [Collection, call number: Non-fiction 394.2663 Bu]

Signed-off-by: Barbara Johnson <barbara.johnson@bedfordtx.gov>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>