[jdk17u-dev] RFR: 8222323: ChildAlwaysOnTopTest.java fails with "RuntimeException: Failed to unset alwaysOnTop"

[Victor Rudometov]

Backport for https://bugs.openjdk.org/browse/JDK-8222323 ChildAlwaysOnTopTest.java fails with "RuntimeException: Failed to unset alwaysOnTop"

Simple clean backport for test failure.
Tests pass, manual test check pass on windows.

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Commit messages:
 - Backport 837928ba7955dbfd4a9c966209c3469c0fb5e195

Changes: https://git.openjdk.org/jdk17u-dev/pull/776/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=776&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8222323
  Stats: 223 lines in 2 files changed: 128 ins; 35 del; 60 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/776.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev pull/776/head:pull/776

PR: https://git.openjdk.org/jdk17u-dev/pull/776