[lworld] RFR: 8378840: [lworld] JFR: Update tests for --enable-preview flag

[Markus Grönlund]

Greetings,

ProcessTools.createLimitedTestJavaProcessBuilder() is used in a few JFR tests. The limited version does not propagate the --enable-preview flag to the process spawned.

For this to work correctly, for some tests, ProcessTools.createTestJavaProcessBuilder(), must be used instead. 

Testing: jdk_valhalla, hotspot_valhalla, hotspot_valhalla_runtime, jdk_jfr

Thanks
Markus

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Commit messages:
 - 8378840

Changes: https://git.openjdk.org/valhalla/pull/2181/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=2181&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8378840
  Stats: 8 lines in 4 files changed: 0 ins; 0 del; 8 mod
  Patch: https://git.openjdk.org/valhalla/pull/2181.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/2181/head:pull/2181

PR: https://git.openjdk.org/valhalla/pull/2181