[jdk11u-dev] RFR: 8315863: [GHA] Update checkout action to use v4

[Aleksey Shipilev]

Semi-clean backport to improve GHA reliability. It does not apply cleanly, because the relevant block for GTest acquisition is missing in 11u.

Additional testing:
 - [ ] GHA

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

Commit messages:
 - Backport b74805d38395ca8be9308d882bf6b84e93714849

Changes: https://git.openjdk.org/jdk11u-dev/pull/2135/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2135&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8315863
  Stats: 6 lines in 6 files changed: 0 ins; 0 del; 6 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2135.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2135/head:pull/2135

PR: https://git.openjdk.org/jdk11u-dev/pull/2135