Prior to this commit, an `ClientHttpRequestInterceptor` implementation
could delegate HTTP calls to the next `ClientHttpRequestExecution` only
once. Calling the execution would advance to the next interceptor in the
chain in a mutable fashion for the entire lifetime of the current
exchange.
This commit changes the implementation of `InterceptingClientHttpRequest`
so that a `ClientHttpRequestInterceptor` implementation can call
`ClientHttpRequestExecution#execute` multiple times.
This is especially useful for interceptors in case they want to issue
other HTTP requests without needing another `RestTemplate` or
`RestClient` instance provided out of band.
Closes gh-34169
e8e722fb59