[jdk21u-dev] RFR: 8328705: GHA: Cross-compilation jobs do not require build JDK

[Aleksey Shipilev]

Clean backport to improve GHA parallelism.

Additional testing:
 - [ ] GHA

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Commit messages:
 - Backport 29ba4b7d1e62a834c1693fe6ad383c19467afc81

Changes: https://git.openjdk.org/jdk21u-dev/pull/403/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=403&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8328705
  Stats: 11 lines in 2 files changed: 0 ins; 10 del; 1 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/403.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/403/head:pull/403

PR: https://git.openjdk.org/jdk21u-dev/pull/403