[jdk11u-dev] RFR: 8210338: Better output for GenerationTests.java

[Amos Shi]

Backport of [JDK-8210338](https://bugs.openjdk.org/browse/JDK-8210338)

Testing
- Local: Test passed on `MacOS 14.6.1` on Apple M1 Max
  - `GenerationTests.java`: Test results: passed: 1
- Pipeline: 
- Testing Machine:

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Commit messages:
 - Backport a5f7028279d61313b2293bbac3eaba0c880a7430

Changes: https://git.openjdk.org/jdk11u-dev/pull/2916/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2916&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8210338
  Stats: 13 lines in 1 file changed: 4 ins; 0 del; 9 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2916.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2916/head:pull/2916

PR: https://git.openjdk.org/jdk11u-dev/pull/2916