RFR: 8358003: KlassTrainingData initializer reads garbage holder

[Igor Veresov]

Simplify KlassTrainingData constructor. The lines in question come from the old pre-CDS world. They are not needed anymore.

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Commit messages:
 - Cleanup with KlassTrainingData constructor

Changes: https://git.openjdk.org/jdk/pull/25623/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25623&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8358003
  Stats: 17 lines in 1 file changed: 0 ins; 13 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/25623.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25623/head:pull/25623

PR: https://git.openjdk.org/jdk/pull/25623