[lworld] RFR: 8369921: [lworld] Remove caches of primitive wrapper classes

[Roger Riggs]

Disable use of wrapper cached values when --enable-preview and add javadoc descriptions for enable-preview.
The wrapper classes are Byte, Short, Character, Integer, and Long.

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Commit messages:
 - 8369921: [lworld] Remove caches of primitive wrapper classes

Changes: https://git.openjdk.org/valhalla/pull/1685/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1685&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8369921
  Stats: 117 lines in 5 files changed: 70 ins; 0 del; 47 mod
  Patch: https://git.openjdk.org/valhalla/pull/1685.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1685/head:pull/1685

PR: https://git.openjdk.org/valhalla/pull/1685