Prior to this commit, gh-31936 enabled content negotiation for
`@ExceptionHandler` annotated methods in Spring MVC and WebFlux.
In the case of WebFlux, HTTP clients sending invalid media types in the
"Accept" request header would fail with a `NotAcceptableStatusException`
This exception would be handled with an HTTP 406 response status,
instead of processing the original exception.
This commit ensures that invalid media types are ignored during the
exception handling phase and that we fall back to "*/*".
Fixes gh-32878
51f6e78e25