RFR: 8372307: Update comments to mention native.encoding instead of file.encoding

[Igor Rudenko]

The `file.encoding` system property is no longer used by the JDK.
Updated code comments to reference the correct replacement: `native.encoding`.

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Commit messages:
 - Merge branch 'openjdk:master' into fix-inaccuracy-in-comments
 - Fix inaccuracy in comments

Changes: https://git.openjdk.org/jdk/pull/27004/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27004&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8372307
  Stats: 2 lines in 2 files changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/27004.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27004/head:pull/27004

PR: https://git.openjdk.org/jdk/pull/27004