RFR: 8343150: Remove URLClassLoader.getPermissions after JEP 486 integration

[Jaikiran Pai]

Can I please get a review of this change which removes the `getPermissions()` method from the `URLClassLoader`? This addresses https://bugs.openjdk.org/browse/JDK-8343150.

With the SecurityManager implementation removed through JEP 486, this method of the `URLClassLoader` is no longer relevant.

No new tests have been added. tier1 and tier2 testing is currently in progress.

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Commit messages:
 - 8343150: Remove URLClassLoader.getPermissions after JEP 486 integration

Changes: https://git.openjdk.org/jdk/pull/22179/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22179&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8343150
  Stats: 98 lines in 1 file changed: 0 ins; 98 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/22179.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22179/head:pull/22179

PR: https://git.openjdk.org/jdk/pull/22179