Improve test coverage of embedchain/vectordb/elasticsearch.py

[taranjeet]

🚀 The feature

As per this coverage report, https://drive.google.com/file/d/1L8HMFafqvlysc6GWXG8sy4ErVuBusbZP/view the current code coverage is low. We need to improve it.

Motivation, pitch

Better code coverage makes development faster and helps in minimizing the errors.

[Clement-Okolo]

I would like to be assigned this issue