[jdk22u] RFR: 8327137: Add test for ConcurrentModificationException in BasicDirectoryModel

[Alexey Ivanov]

Provides a regression test for [JDK-8323670](https://bugs.openjdk.org/browse/JDK-8323670): _A few client tests intermittently throw ConcurrentModificationException_.

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Commit messages:
 - Backport 9731b1c8b02d957985f4fb40acd93fb67747a9f0

Changes: https://git.openjdk.org/jdk22u/pull/151/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk22u&pr=151&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8327137
  Stats: 273 lines in 1 file changed: 273 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk22u/pull/151.diff
  Fetch: git fetch https://git.openjdk.org/jdk22u.git pull/151/head:pull/151

PR: https://git.openjdk.org/jdk22u/pull/151