net/http: handle server errors after sending GOAWAY [1.18 backport]

[neild]

A closing HTTP/2 server connection could hang forever waiting for a clean shutdown that was preempted by a subsequent fatal error. This failure mode could be exploited to cause a denial of service.

Thanks to Bahruz Jabiyev, Tommaso Innocenti, Anthony Gavazzi, Steven Sprecher, and Kaan Onarlioglu for reporting this.

This was a PRIVATE issue for CVE-2022-27664 tracked in http://b/219507101 and fixed by http://tg/1413887.

[dmitshur]

Since this is in Go1.18.6 milestone, added a "[1.18 backport]" suffix and a CherryPickCandidate label so this doesn't get missed during backport review, but I expect it to get approved as a security fix.

[joedian]

@neild can we add a backport for 1.19 as well?

[neild]

@neild can we add a backport for 1.19 as well?

Created #54376.