RFR: 8257591: Remove suppression of record preview related warnings in java.lang

[Julia Boes]

Records exit preview in JDK 16. This change removes preview related suppression warnings in some source files and removes the '--enable-preview' option for compilation and execution of some tests that use record classes.

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Commit messages:
 - remove --enable-preview in tests
 - remove record related warning suppression

Changes: https://git.openjdk.java.net/jdk/pull/1591/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1591&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8257591
  Stats: 16 lines in 6 files changed: 0 ins; 6 del; 10 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1591.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1591/head:pull/1591

PR: https://git.openjdk.java.net/jdk/pull/1591