RFR: 8331063: Some HttpClient tests don't report leaks

Wed Apr 24 17:53:48 UTC 2024

This patch fixes leak reporting in `ForbiddenHeadTest.java` and `ProxySelectorTest.java`.

The tests were checking for leaks, but the detected problems were not reported to the test harness. Additionally, `ForbiddenHeadTest.java` was holding references to the clients, preventing them from being collected by GC.

The tests continue to pass.

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Commit messages:
 - Fix leak tracking

Changes: https://git.openjdk.org/jdk/pull/18938/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18938&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8331063
  Stats: 30 lines in 2 files changed: 7 ins; 0 del; 23 mod
  Patch: https://git.openjdk.org/jdk/pull/18938.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18938/head:pull/18938

PR: https://git.openjdk.org/jdk/pull/18938