[jdk21u-dev] RFR: 8354415: [Ubuntu25.04] api/java_awt/GraphicsDevice/indexTGF.html#SetDisplayMode - setDisplayMode_REFRESH_RATE_UNKNOWN fails: Height is different on vnc

[Goetz Lindenmaier]

I backport this for parity with 21.0.9-oracle.

Combination of two clean backports.

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Commit messages:
 - backport 18190519e73705281adf3f94d710d000e75b1729
 - backport 18c2e40de75f974858aeb453892e4c7c8d5aa90e

Changes: https://git.openjdk.org/jdk21u-dev/pull/2053/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=2053&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8354415
  Stats: 355 lines in 3 files changed: 347 ins; 1 del; 7 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/2053.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/2053/head:pull/2053

PR: https://git.openjdk.org/jdk21u-dev/pull/2053