RFR: JDK-8311792: java/net/httpclient/ResponsePublisher.java fails intermittently with AssertionError: Found some outstanding operations [v2]

[Darragh Clarke]

> Currently `ResponsePublisher` occasionally fails due to unreleased resources.
> Updated test based on [AbstractThrowingPushPromises](https://github.com/openjdk/jdk/blob/b80001de0c0aeedeb412430660a4727fc26be98b/test/jdk/java/net/httpclient/AbstractThrowingPushPromises.java#L343) to ensure that non-shared clients get closed before further iterations run, this should limit the max number of clients that remain alive during the test.
> 
> I ran tiers 1-3 and everything is passing

Darragh Clarke has updated the pull request incrementally with one additional commit since the last revision:

  Update test/jdk/java/net/httpclient/ResponsePublisher.java
  
  Co-authored-by: Daniel Fuchs <67001856+dfuch at users.noreply.github.com>

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Changes:
  - all: https://git.openjdk.org/jdk/pull/15307/files
  - new: https://git.openjdk.org/jdk/pull/15307/files/91b3a009..06a67462

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15307&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15307&range=00-01

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/15307.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15307/head:pull/15307

PR: https://git.openjdk.org/jdk/pull/15307