Clearer error message for mismatched kbn-version on api request

[epixa]

If you make an API request to Kibana (e.g. the new ingest API) with an outdated kbn-version header, you get the error Browser client is out of date, please refresh the page. This error message is extremely useful when a user experiences while using Kibana in their browser, but it's misleading and unhelpful when encountered when trying to make an API request. We should either make the error message dependent on context or make it general enough to apply to any context.

[epixa]

See the discussion starting at #5213 (comment) for a real world example of this confusion.

[jstoja]

I just faced this issue and I also think the error message could be clearer. This let to think that the UA might come into play, even though it's not.