Remove "deprecated" error headers

> Do you happen to know the truth about headers for error responses?

Not exactly, just that there is one default error handler that sets `X-Platform-Error-Code` but using it isn't exactly standard, so that header may not always come through, but a nearly equivalent value more likely always comes through as the response code. In other words, it may enrich the response, but not having it isn't the end of the world.

There is a comment in the code: `We're no longer using X-Influx-Error and X-Influx-Reference.`, so I'd imagine removing those from the spec is a move in the right direction.

_Originally posted by @glinton in https://github.com/influxdata/openapi/pull/359#issuecomment-1172762118_

Search the OpenAPI specification for X-Influx-Error, X-Influx-Reference, and the deprecated error headers mentioned in the issue. Review the surrounding response definitions, then remove the obsolete header entries and verify that the specification no longer documents them.

Written by the indexing model from the issue text.