Allow proxy between Ent Search Connectors and Elasticsearch

### Problem Description

At the present moment, the Elastic connectors (https://github.com/elastic/connectors/blob/8.11/config.yml and https://www.elastic.co/guide/en/enterprise-search/current/connectors.html) do not have an option to declare a proxy for the connection.

### Proposed Solution
The change would allow connector to communicate with Elasticsearch via a proxy connection.

### Additional Context
In many use cases, due security or just architectural design, all connection must go through a proxy. In the actual scenario, this is impossible for a Ent Search connector limiting it's use cases and usability.

- Stackoverflow for ES python client to leverage proxy: https://stackoverflow.com/questions/32778235/elasticsearch-python-proxy
- Elasticsearch Python Client workaround: https://github.com/elastic/elastic-transport-python/issues/53#issuecomment-1447903214