RFR: 8255863: Clean up test/jdk/java/lang/invoke/defineHiddenClass/BasicTest.java

[Mandy Chung]

test/jdk/java/lang/invoke/defineHiddenClass/BasicTest.java tests a record class.
This test no longer needs to be run with --enable-preview.

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Commit messages:
 - 8255863: Clean up test/jdk/java/lang/invoke/defineHiddenClass/BasicTest.java

Changes: https://git.openjdk.java.net/jdk/pull/1048/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1048&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8255863
  Stats: 3 lines in 1 file changed: 0 ins; 1 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1048.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1048/head:pull/1048

PR: https://git.openjdk.java.net/jdk/pull/1048