RFR: 8373517: Revert the macos Tahoe specific change done in JDK-8359830

[Jaikiran Pai]

Can I please get a review of this change which reverts the macos Tahoe specific change we had done in https://bugs.openjdk.org/browse/JDK-8359830? As noted in https://bugs.openjdk.org/browse/JDK-8373517, Apple addressed the underlying issue in a 26.0 Beta release and we no longer require this change in the JDK.

The revert in this PR was done with a `git revert` of 8df6b2c4a355751cd8ca37cc5932be66bccaa123. That original commit had updated a jtreg test to verify the `os.version` system property reported by the JDK on macos. The commit in this PR retains that test because it's useful even without the source changes done in that older commit.

tier1, tier2 and tier3 testing of this change completed without any related issues. I've verified that macos 26.x was one of the hosts that was picked up in those test runs.

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Commit messages:
 - copyright year
 - keep the additional testing in OsVersionTest
 - Revert "8359830: Incorrect os.version reported on macOS Tahoe 26 (Beta)"

Changes: https://git.openjdk.org/jdk/pull/28768/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=28768&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8373517
  Stats: 34 lines in 1 file changed: 0 ins; 18 del; 16 mod
  Patch: https://git.openjdk.org/jdk/pull/28768.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28768/head:pull/28768

PR: https://git.openjdk.org/jdk/pull/28768