Elasticsearch url is hardcoded to http://localhost:9200

The url should be set using an env variable

### Expected Behaviour
http://localhost:9200 should be the default if env variable ELASTICSEARCH_URL is missing

### Actual Behaviour
Elasticsearch url is hardcoded to http://localhost:9200

Search the repository for the hardcoded http://localhost:9200 value and the Elasticsearch client setup; no file is named in the issue. Check the relevant tests or run the applicable test suite, then verify that ELASTICSEARCH_URL overrides the value and the default remains localhost:9200 when it is absent.

Written by the indexing model from the issue text.