Bug 36439: Remove duplicate section in columns_settings

Bug 36439: Remove duplicate section in columns_settings

   The patch for bug 33575 was carelessely applied so
   the holds section was overwritten by a duplicated
   section which cause the table configuration for
   the holds-to-pull table to be missing.

   Test plan:

   * Place a hold on a record that has items (so there is at least one hold to pull)
   * Go to the page "holds to pull" and verify that the column settings are present
     to the left above the table (<cog wheel icon> Columns).

     NOTE: the column settings are cached, so you need to reset memcached
     between tests if you want to test with and without the patch.

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>