[lworld] RFR: 8373506: [lworld] Disable currently unsupported builds in GHA

[Axel Boldt-Christmas]

The lworld branch does currently not support zero, Shenandoah GC nor other cpu architectures than x86_64 and aarch64.

I suggest we disable these builds from being run in GHA, to reduce noise and wasted machine hours.

Once the these specific VM configurations or features have been implemented for lworld we can reenable the actions.

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Commit messages:
 - Disable currently unsupported build linux-x64-hs-zero in GHA
 - Disable currently unsupported cross compilation targets in GHA
 - Disable ShenandoahGC in GHA

Changes: https://git.openjdk.org/valhalla/pull/1786/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1786&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8373506
  Stats: 46 lines in 5 files changed: 3 ins; 0 del; 43 mod
  Patch: https://git.openjdk.org/valhalla/pull/1786.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1786/head:pull/1786

PR: https://git.openjdk.org/valhalla/pull/1786