RFR: 8329292: Fix missing cleanups in java.management and jdk.management

[Magnus Ihse Bursie]

For some reason, I missed adding the new standard header for SetupJdkLibrary in java.management and jdk.management. I also missed to remove a now superfluous CFLAGS_JDKLIB in libmanagement_ext.

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Commit messages:
 - 8329292: Fix missing cleanups in java.management and jdk.management

Changes: https://git.openjdk.org/jdk/pull/18538/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18538&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8329292
  Stats: 5 lines in 2 files changed: 4 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/18538.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18538/head:pull/18538

PR: https://git.openjdk.org/jdk/pull/18538