[jdk21u-dev] RFR: 8328948: GHA: Restoring sysroot from cache skips the build after JDK-8326960

[Aleksey Shipilev]

Fixes a recent GHA regression.

Additional testing:
 - [ ] GHA, first run passes cross-builds
 - [ ] GHA, second run passes cross-builds

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Commit messages:
 - Backport 447436e18c754424a62af5135fb3a8973564091d

Changes: https://git.openjdk.org/jdk21u-dev/pull/408/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=408&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8328948
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/408.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/408/head:pull/408

PR: https://git.openjdk.org/jdk21u-dev/pull/408