[lworld] RFR: 8336141: [lworld] Remove remains of java.lang.NonTearable support

[Frederic Parain]

Code cleanup, and test upgrade to work with the JEP 401 model.

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Commit messages:
 - j.l.NonTearable cleanup

Changes: https://git.openjdk.org/valhalla/pull/1165/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1165&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8336141
  Stats: 28 lines in 2 files changed: 14 ins; 4 del; 10 mod
  Patch: https://git.openjdk.org/valhalla/pull/1165.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1165/head:pull/1165

PR: https://git.openjdk.org/valhalla/pull/1165