Prior to this commit, the HTTP interceptor model used for `RestTemplate`
and `RestClient` would not update the "Content-Length" request header,
even when the request body had been updated by a
`ClientHttpRequestInterceptor`.
Even though this is the `ClientHttpRequestInterceptor`'s responsibility
(along with the content type and encoding changes if needed), this
would result in invalid requests. This invalid situation can be detected
by `InterceptingClientHttpRequest`.
This commit ensures that such situations are detected and fixed
automatically by setting the Content-Length header to the actual body
size, right before executing the actual request, after all interceptors
are done.
Closes gh-33459
aca264942d