[jdk11u-dev] RFR: 8202790: DnD test DisposeFrameOnDragTest.java does not clean up

[Amos Shi]

Backport of [JDK-8202790](https://bugs.openjdk.org/browse/JDK-8202790)
- Clean Backport
- Test Succeeded in local Dev Apple M1 Laptop

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Commit messages:
 - Backport 102a305f73d52d8e378de46c3c0b170db0f2c8af

Changes: https://git.openjdk.org/jdk11u-dev/pull/2375/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2375&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8202790
  Stats: 9 lines in 2 files changed: 7 ins; 1 del; 1 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2375.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2375/head:pull/2375

PR: https://git.openjdk.org/jdk11u-dev/pull/2375