[lworld] RFR: 8327836: [lworld] update java/lang/invoke/VarHandles tests with preview feature enabled

[Mandy Chung]

Update test/jdk/java/lang/invoke/VarHandles valhalla tests with `@enablePreview`

-------------

Commit messages:
 - 8327836: [lworld] update java/lang/invoke/VarHandles tests with preview feature enabled

Changes: https://git.openjdk.org/valhalla/pull/1043/files
 Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1043&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8327836
  Stats: 6 lines in 6 files changed: 6 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/valhalla/pull/1043.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1043/head:pull/1043

PR: https://git.openjdk.org/valhalla/pull/1043