Bug 30954: (bug 27344 follow-up) Remove background_jobs_update_elastic_index.inc

Bug 30954: (bug 27344 follow-up) Remove background_jobs_update_elastic_index.inc

includes/background_jobs_update_elastic_index.inc
vs
includes/background_jobs/update_elastic_index.inc

Both exist and have been added by bug 27344.
The first one is not used.

Test plan:
  git grep background_jobs_update_elastic_index.inc
must not return any occurrences (outside of POs)

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
(cherry picked from commit cfb293a08a3a343213389c681a0a55be936cfd13)

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>