cross build arm64 gce disk format is not supported on x86

[chunfuwen]

On x86 Fedora 40 machine ,execute below command
[root@xx httpd]# sudo podman run     --rm     -it     --privileged     --pull=newer     --security-opt label=type:unconfined_t     -v $(pwd)/output:/output     -v /var/lib/containers/storage:/var/lib/containers/storage     quay.io/centos-bootc/bootc-image-builder:latest     --type gce --target-arch arm64     --local     localhost/manifest-test
Generating manifest manifest-gce.json
WARNING: target-arch is experimental and needs an installed 'qemu-user' package
DONE
Building manifest-gce.json
Export gce not found in ['build', 'ostree-deployment', 'image', 'qcow2', 'vmdk', 'ovf', 'archive']
Failed
2024/10/14 07:27:46 error: cannot run osbuild: running osbuild failed: exit status 1