[lworld] RFR: 8370341: [lworld] More follow-up work from the array metadata re-work

[Tobias Hartmann]

This is a follow-up from [JDK-8366705](https://bugs.openjdk.org/browse/JDK-8366705) (and [JDK-8366668](https://bugs.openjdk.org/browse/JDK-8366668)), resolving remaining ToDos.

I filed [JDK-8370880](https://bugs.openjdk.org/browse/JDK-8370880) for the last missing piece of splitting `ciObjArrayKlass` into `ciRefArrayKlass` and `ciFlatArrayKlass` to be consistent with the runtime code (this is "just" a refactoring).

Thanks,
Tobias

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Commit messages:
 - Style fix
 - v6
 - Merge
 - v5
 - v4
 - v3
 - v1
 - v0

Changes: https://git.openjdk.org/valhalla/pull/1709/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1709&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8370341
  Stats: 1315 lines in 30 files changed: 968 ins; 212 del; 135 mod
  Patch: https://git.openjdk.org/valhalla/pull/1709.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1709/head:pull/1709

PR: https://git.openjdk.org/valhalla/pull/1709