RFR: 8349513: Remove unused BUILD_JDK_JTREG_LIBRARIES_JDK_LIBS_libTracePinnedThreads

[Jiangli Zhou]

Please review this minor cleanup. The related jtreg test, TracePinnedThreads.java/libTracePinnedThreads.c has already been removed by https://github.com/openjdk/jdk/pull/21565 work (for [JDK-8338383](https://bugs.openjdk.org/browse/JDK-8338383)).

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Commit messages:
 - Remove unused BUILD_JDK_JTREG_LIBRARIES_JDK_LIBS_libTracePinnedThreads.

Changes: https://git.openjdk.org/jdk/pull/23482/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=23482&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8349513
  Stats: 1 line in 1 file changed: 0 ins; 1 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/23482.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23482/head:pull/23482

PR: https://git.openjdk.org/jdk/pull/23482