Bug 18897: Add skipping to t/db_dependent/Koha_SearchEngine_Elasticsearch_Search.t

Bug 18897: Add skipping to t/db_dependent/Koha_SearchEngine_Elasticsearch_Search.t

Test Plan:
$ git fetch
$ git checkout -b bug_18897 origin/master
$ sudo apt-get remove libcatmandu-store-elasticsearch-perl
$ prove t/db_dependent/Koha_SearchEngine_Elasticsearch_Search.t
-- nasty failure.
$ git bz apply 18897
-- apply all the patches
$ prove t/db_dependent/Koha_SearchEngine_Elasticsearch_Search.t
-- nicer skip message
run the koha qa test tools

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>