render non-ElasticsearchException in ILM

[talevy]

ILM was rendering exceptions using the exception helper that
basically ignores simply rendering non-elasticsearch exceptions when
no details are desired. This commit updates the method used to still be
a rather simple rendering of the exception. The rendering lacks
all the causes, but does a sufficient job in rendering the top-level
message for one of our most expected exceptions... IllegalArgumentException

Previous Example:

{
  "test": {
   ...
    "step_info": {
      "error": "No ElasticsearchException found"
    }
  }
}

now the error will render { "type": "illegal_argument_exception", "message": "an explanation" }

[elasticmachine]

Pinging @elastic/es-core-infra

[talevy]

@colings86 I do not like this option, but I don't get why there are no nice options in ElasticsearchException. Might be worth updating core to be friendlier, but this may be fine for now?

unless I am missing another option. One thing I thought about was wrapping the exception in an ElasticsearchException...

[colings86]

Could you explain what you don't like about this option. Is it just that it doesn't render the complete exception stack?

We render the full exception stack in exceptional REST responses so we should be able to do the same as we do there?

[talevy]

We render the full exception stack in exceptional REST responses so we should be able to do the same as we do there?

I thought you left detailed=false on purpose. I am all for more information