RFR: 8376479: Http3 test server thread deadlock in ThrowingPublishersInRequest [v3]

[Daniel Jeliński]

> This fixes a deadlock between the thread that reads from the RequestBodyInputStream and the thread that tries to close it in response to a stream reset. See the linked JBS ticket for details.
> 
> Tier1 and tier2 tests continue to pass. I verified that with this change there are no busy threads at the end of the test.

Daniel Jeliński has updated the pull request incrementally with two additional commits since the last revision:

 - Send stop_sending if the InputStream is closed
 - Close the stream atomically

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/29448/files
  - new: https://git.openjdk.org/jdk/pull/29448/files/a8a5415c..52230a48

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=29448&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=29448&range=01-02

  Stats: 33 lines in 1 file changed: 13 ins; 10 del; 10 mod
  Patch: https://git.openjdk.org/jdk/pull/29448.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29448/head:pull/29448

PR: https://git.openjdk.org/jdk/pull/29448