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

[Christian Stein]

> 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

-------------

Changes:
  - all: https://git.openjdk.org/jtreg/pull/254/files
  - new: https://git.openjdk.org/jtreg/pull/254/files/e5027369..f13ff38b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jtreg&pr=254&range=01
 - incr: https://webrevs.openjdk.org/?repo=jtreg&pr=254&range=00-01

  Stats: 2 lines in 1 file changed: 0 ins; 2 del; 0 mod
  Patch: https://git.openjdk.org/jtreg/pull/254.diff
  Fetch: git fetch https://git.openjdk.org/jtreg.git pull/254/head:pull/254

PR: https://git.openjdk.org/jtreg/pull/254