[jdk21u-dev] RFR: 8339791: Refactor MiscUndecorated/ActiveAWTWindowTest.java

[Goetz Lindenmaier]

I backport this for parity with 21.0.11-oracle.

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Commit messages:
 - Backport a306f88a8456be454f4954c7e4fb8a1273344b5b

Changes: https://git.openjdk.org/jdk21u-dev/pull/2621/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=2621&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8339791
  Stats: 160 lines in 1 file changed: 26 ins; 89 del; 45 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/2621.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/2621/head:pull/2621

PR: https://git.openjdk.org/jdk21u-dev/pull/2621