RFR: 8315863: [GHA] Update checkout action to use v4

[Christian Stein]

Please review this change to update all workflows to use `actions/checkout at v4`.

Find the associated release notes here: https://github.com/actions/checkout/releases/tag/v4.0.0

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Commit messages:
 - 8315863: [GHA] Update checkout action to use v4

Changes: https://git.openjdk.org/jdk/pull/15620/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15620&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8315863
  Stats: 7 lines in 7 files changed: 0 ins; 0 del; 7 mod
  Patch: https://git.openjdk.org/jdk/pull/15620.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15620/head:pull/15620

PR: https://git.openjdk.org/jdk/pull/15620