This commit adapts the error controller tests that need the request
to fail with a bind issue, and simulate the behavior of
ModelAttributeMethodProcessor.
As of Spring Framework 6.0.x, this processor no longer throws a
BindingException, but rather a MethodArgumentNotValidException and
the handing of BindException itself is deprecated.
This makes sure that those tests can smoothly be executed against
Spring Framework 6.2.x as throwing a BindingException now results
into an unresolved exception, and an internal server error rather than
the expected bad request.
See gh-39767
f6e4bede09