[jdk17u-dev] RFR: 8305906: HttpClient may use incorrect key when finding pooled HTTP/2 connection for IPv6 address

[Jaikiran Pai]

Can I please get a review for this change which backports the fix that was done in https://bugs.openjdk.org/browse/JDK-8305906?

The fix in the source is a clean backport. However, the newly introduced test in mainline uses a test specific libraries which aren't the same in 17u. As a result, the tests `test/jdk/java/net/httpclient/http2/ConnectionReuseTest.java` had conflicts. I have manually updated relevant parts of that test to make it use the test libraries that are available and applicable in 17u. 

I have also verified that the test fails (as expected) if I undo the source change and passes when I re-introduce the source change. Additionally, I have run this test in our CI to verify that it passes.

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Commit messages:
 - remove unintentional debug system property
 - test changes to accomodate test infrastructure in 17u
 - Backport 3ccb3c0e09f9a414229d3f76031f3fc8f271c936

Changes: https://git.openjdk.org/jdk17u-dev/pull/2121/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=2121&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8305906
  Stats: 211 lines in 4 files changed: 199 ins; 4 del; 8 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/2121.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/2121/head:pull/2121

PR: https://git.openjdk.org/jdk17u-dev/pull/2121