[lworld] Integrated: 8328636: [lworld] runtime/clinit/ClassInitBarrier.java fails because of a compilation error

[Frederic Parain]

Simple fix enabling preview mode for the whole test and removing the -XX:EnableValhalla flag.

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Commit messages:
 - Fix enable preview flag

Changes: https://git.openjdk.org/valhalla/pull/1053/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1053&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8328636
  Stats: 15 lines in 1 file changed: 1 ins; 0 del; 14 mod
  Patch: https://git.openjdk.org/valhalla/pull/1053.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1053/head:pull/1053

PR: https://git.openjdk.org/valhalla/pull/1053