RFR: 8250840: some tests use --enable-preview unnecessarily

[Jan Lahoda]

8250840: some tests use --enable-preview unnecessarily

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

Commit messages:
 - 8250840: some tests use --enable-preview unnecessarily

Changes: https://git.openjdk.java.net/jdk/pull/41/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=41&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8250840
  Stats: 11 lines in 6 files changed: 0 ins; 0 del; 11 mod
  Patch: https://git.openjdk.java.net/jdk/pull/41.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/41/head:pull/41

PR: https://git.openjdk.java.net/jdk/pull/41