Bug 20607: Make Koha::SearchEngine::Elasticsearch::reset_elasticsearch_mappings take...

Bug 20607: Make Koha::SearchEngine::Elasticsearch::reset_elasticsearch_mappings take weight into account

Test plan:
  - apply this patch,
  - edit admin/searchengine/elasticsearch/mappings.yaml
    to add weight for some fields,
  - go to admin > search engine configuration,
  - reset your mappings (add ?op=reset&i_know_what_i_am_doing=1 to url),
  - check that weights you've added are set

Signed-off-by: Nicolas Legrand <nicolas.legrand@bulac.fr>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>