[jdk21u] RFR: 8309761: Leak class loader constraints

[Zhengyu Gu]

A clean backport to fix memory leak.

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Commit messages:
 - Backport 8e4e6b056c5ecf731f84a71e4e319d2a27734ec2

Changes: https://git.openjdk.org/jdk21u/pull/6/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk21u&pr=6&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8309761
  Stats: 3 lines in 1 file changed: 3 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk21u/pull/6.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u.git pull/6/head:pull/6

PR: https://git.openjdk.org/jdk21u/pull/6