[jdk17u] RFR: 8273359: CI: ciInstanceKlass::get_canonical_holder() doesn't respect instance size

[Tobias Hartmann]

Backport of [JDK-8273359](https://bugs.openjdk.java.net/browse/JDK-8273359). Applies cleanly. Approval is pending.

Thanks,
Tobias

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Commit messages:
 - 8273359: CI: ciInstanceKlass::get_canonical_holder() doesn't respect instance size

Changes: https://git.openjdk.java.net/jdk17u/pull/105/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk17u&pr=105&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8273359
  Stats: 68 lines in 5 files changed: 61 ins; 0 del; 7 mod
  Patch: https://git.openjdk.java.net/jdk17u/pull/105.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17u pull/105/head:pull/105

PR: https://git.openjdk.java.net/jdk17u/pull/105