RFR: 8333804: java/net/httpclient/ForbiddenHeadTest.java threw an exception with 0 failures

[Daniel Fuchs]

The test failed because the shared HttpClients were not garbage collected in the imparted time.
The timeout of 500ms to wait for the clients to clean up is sufficient most of the time but rather small, I suspect a bit more time was needed in that instance.

The fix raises the timeout to 1500ms.

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Commit messages:
 - 8333804

Changes: https://git.openjdk.org/jdk/pull/19600/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19600&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8333804
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/19600.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19600/head:pull/19600

PR: https://git.openjdk.org/jdk/pull/19600