RFR: 7903969: Update year in copyright message [v2]

[Iris Clark]

On Wed, 12 Mar 2025 15:41:38 GMT, Christian Stein <cstein at openjdk.org> wrote:

>> Please review this change updating the second year of the copyright to 2025.
>> 
>> This PR also removes the copyright from command-line printouts of `jtreg` and `jtdiff`, for example in `jtreg --help` calls.
>
> Christian Stein has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Remove unused message

Marked as reviewed by iris (Reviewer).

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PR Review: https://git.openjdk.org/jtreg/pull/254#pullrequestreview-2679135805