[jdk17u-dev] RFR: 8314658: [17u] GHA: Sync up debian-version for cross-builds

[Aleksey Shipilev]

[JDK-8283929](https://bugs.openjdk.org/browse/JDK-8283929) brought the change to cross-compilation configs that bootstrapped with "buster". This was a deviation from the original change, AFAICS because the runners were still on Ubuntu 20.04.

After the upgrade to Ubuntu 22.04 runner with [JDK-8312511](https://bugs.openjdk.org/browse/JDK-8312511), it would make more sense to bootstrap with "bullseye", like current mainline that also runs with 22.04 does. This avoids accidental infra breakages that would be only detectable on 17u, not on mainline.

Additional testing:
 - [ ] GHA

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Commit messages:
 - Fix

Changes: https://git.openjdk.org/jdk17u-dev/pull/1681/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=1681&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8314658
  Stats: 4 lines in 1 file changed: 0 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/1681.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/1681/head:pull/1681

PR: https://git.openjdk.org/jdk17u-dev/pull/1681