Improve error reporting for ES queries

[roborourke]

Error reporting for elastic search issues is not as useful as it could be for debugging in cloud environments. It's not currently possible to surface the true source of an error due to the lack of backtrace data so we need to surface more data if possible in the error log, or if possible trace ES requests in XRay.

Potential improvements:

• Include the JSON query in the error log to provide some clue as to its origin
• Review types of ES error and provide potential mitigations in the error log - ideally with links to an FAQ section in the docs

Related to #137