[elasticsearch] safe-guard when the body is already encoded

[palazzem]

What it does

• if the Elasticsearch perform_request fails for our instrumentation, ensure the original method is called
• handles the case where the body is already encoded as a string; in that case the JSON.generate() will fail so we use it as is

Note

Third party libraries encode the body as a String (i.e. Chewy) so we should handle that case

[palazzem]

relaxing here, we will take in consideration Rubocop in another PR

[ufoot]

👍

[ufoot]

Yes, generally speaking, encapsulating our things like this makes sense, 100% for ensuring the "real" code is running no matter what.

[galdor]

LGTM. Note that you can use super without arguments.