So far the in-flight request circuit breaker has only accounted for the
on-the-wire representation of a request. However, we convert the raw
request into XContent internally which increases the overhead.
Therefore, we increase the value of the corresponding setting
`network.breaker.inflight_requests.overhead` from one to two. While this
value is still rather conservative (we assume that the representation as
structured objects has no overhead compared to the byte[]), it is closer
to reality than the current value.
Relates #31613
3d53daeb2f