[jdk17u-dev] RFR: 8343804: Show the default time zone with -XshowSettings option

[Goetz Lindenmaier]

I backport this for parity with 17.0.17-oracle.

Same edits as in 21 backport. I will make it reference the 21 commit once available, the it should be clean.

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Commit messages:
 - Backport 0329855831102a48abf14b5befc933f84dfd3460

Changes: https://git.openjdk.org/jdk17u-dev/pull/3739/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=3739&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8343804
  Stats: 8 lines in 2 files changed: 6 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/3739.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/3739/head:pull/3739

PR: https://git.openjdk.org/jdk17u-dev/pull/3739