BUG/MINOR: mux-h2: Reset streams with NO_ERROR code if full response was already...

BUG/MINOR: mux-h2: Reset streams with NO_ERROR code if full response was already sent

On frontend side, when a stream is shut while the response was already fully
sent, it was cancelled by sending a RST_STREAM(CANCEL) frame. However, it is
not accurrate. CANCEL error code must only be used if the response headers
were sent, but not the full response. As stated in the RFC 9113, when the
response was fully sent, to stop the request sending, a RST_STREAM with an
error code of NO_ERROR must be sent.

This patch should solve the issue #1219. It must be backported to all stable
versions.