podvm-mkosi: sshd failed for s390x fedora image

[genjuro214]

For debug image, sshd service failed to start on s390x:

Apr 15 02:35:49 cdlleili-custom sshd[1353]: sshd: no hostkeys available -- exiting.
Apr 15 02:36:31 cdlleili-custom sshd[1395]: Unable to load host key: /run/ssh/ssh_host_rsa_key
Apr 15 02:36:31 cdlleili-custom sshd[1395]: Unable to load host key: /run/ssh/ssh_host_ecdsa_key
Apr 15 02:36:31 cdlleili-custom sshd[1395]: Unable to load host key: /run/ssh/ssh_host_ed25519_key
Apr 15 02:36:31 cdlleili-custom sshd[1395]: sshd: no hostkeys available -- exiting.

ssh config is overwritten by extra package: mkosi.skeleton-debug/etc/ssh/sshd_config

However, it conflicts with cloud-init on s390x, so failed to generate ssh host keys at /run/ssh. cloud-init will generate host keys at /etc/ssh.

So just keep the default ssh config for s390x