[lworld] RFR: 8370687: [lworld] Improve before constructor has been called error message

[Chen Liang]

Now we have an early construction by default mode on for value classes, where post-super calls requires explicit constructor invocation. We can tweak the messages slightly to accomplish this.

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Commit messages:
 - 8370687: [lworld] Improve before constructor has been called error message

Changes: https://git.openjdk.org/valhalla/pull/1705/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1705&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8370687
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/valhalla/pull/1705.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1705/head:pull/1705

PR: https://git.openjdk.org/valhalla/pull/1705