[jdk21u-dev] RFR: 8343804: Show the default time zone with -XshowSettings option

[Goetz Lindenmaier]

I backport this for parity with 17.0.17-oracle.

In the test, I had to resolve the @bug line.
Also I omitted the edit of one test function that was added in 22.

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Commit messages:
 - Backport 0329855831102a48abf14b5befc933f84dfd3460

Changes: https://git.openjdk.org/jdk21u-dev/pull/1962/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1962&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8343804
  Stats: 7 lines in 2 files changed: 6 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/1962.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/1962/head:pull/1962

PR: https://git.openjdk.org/jdk21u-dev/pull/1962