Bug 24552: Be compatible with Search::Elasticsearch 6.00

Bug 24552: Be compatible with Search::Elasticsearch 6.00

There is no need to specify the `client` param here because
'5_0::Direct' is the default value for Search::Elasticsearch 5.x and it
breaks when Search::Elasticsearch 6.x is installed

Test plan:
1. Apply the patch
2. Make sure you have Search::Elasticsearch 5.x
3. Reload starman
4. Verify that search works
5. Install Search::Elasticsearch 6.x
6. Reload starman
7. Verify that search works

Signed-off-by: Michal Denar <black23@gmail.com>
Signed-off-by: Ere Maijala <ere.maijala@helsinki.fi>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>