http: fix closing HTTP 1.x connection

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 (closed).