RFR: 8358003: KlassTrainingData initializer reads garbage holder [v3]

[Igor Veresov]

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

Igor Veresov has updated the pull request incrementally with two additional commits since the last revision:

 - More changes
 - Use dedicated OopStorage

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/25623/files
  - new: https://git.openjdk.org/jdk/pull/25623/files/85a71619..f8a9b4a3

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=25623&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=25623&range=01-02

  Stats: 32 lines in 4 files changed: 20 ins; 8 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