RFR: 8310540: G1: Verification should use raw oop decode functions

[Thomas Schatzl]

Hi all,

  please review this PR that changes a `CompressedOops::decode_not_null` to a `decode_raw_not_null`. The reason is that doing so allows the method to proceed to print better debugging information compared to the failing assert in `decode_not_null`.

Testing: gha, local compilation

Thanks,
  Thomas

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Commit messages:
 - initial version

Changes: https://git.openjdk.org/jdk/pull/14592/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14592&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8310540
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/14592.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14592/head:pull/14592

PR: https://git.openjdk.org/jdk/pull/14592