When the client closes the stream, then underlying HTTP 1.x
connection must be terminated in any of the following cases:
- The server uses HTTP version 1.0.
- The server specified the "close" token in the Connection header line
  of the HTTP response header.
- Fewer bytes than specified in the Content-Length header line of the
  HTTP response header were read.
- The response body is encoded with chunked encoding and the end of the
  body has not been reached.

In the first two cases, flag `connection_close` will be set. It was
write-only before this patch.

In the third case, the `content_length` will be non-zero but not
unknown (`UINTMAX_MAX`).

The last case is already handled by the chunked encoding decoder.

Fixes #26084.

(cherry picked from commit 113e98f6)