[lworld] RFR: 8370951: [lworld] Value record ClassCircularityError

[Paul Hübner]

Hi all,

When we encounter situations where we can't preload, for example if two value classes refer to each other, **may** not be able to do flattening as we cannot compute the field layout. We have log messages as a hint to application or library developers to let them know of that fact. They are very useful for debugging. However, retaining them at the `warning` level means they are shown by default. This may be misleading, as seeing e.g. `ClassCircularityError` in a log may indicate that something has gone gravely wrong, which is not the case with preload failures. This PR relegates all preload failure logs to level `info`, such that the information is opt-in and will not unnecessarily cause confusion.

Testing: tier 1.

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Commit messages:
 - Forgot to update a test.
 - Relegate preload logs to info.

Changes: https://git.openjdk.org/valhalla/pull/1710/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1710&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8370951
  Stats: 32 lines in 6 files changed: 0 ins; 0 del; 32 mod
  Patch: https://git.openjdk.org/valhalla/pull/1710.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1710/head:pull/1710

PR: https://git.openjdk.org/valhalla/pull/1710