fix: use correct sshd_config.d/ ordering

Commit 3b2eeb0171 wrongly backported a change to not modify
/etc/ssh/sshd_config . The correct fix from ubuntu/master is
3b2eeb0171 where the file is named 60-cloudimg-settings.conf
instead of 10-cloudimg-settings.conf.

This fixes problems with cloud-init which does write
50-cloud-init.conf which should have higher priority than the provided
file from the image.

live-build/ubuntu-cpc/hooks.d/chroot/052-ssh_authentication.chroot

@@ -1,5 +1,8 @@
 #!/bin/bash
 
-cat << EOF >> "/etc/ssh/sshd_config.d/10-cloudimg-settings.conf"
+# NOTE: the file number needs to be **higher** than the one
+# cloud-init writes (cloud-init uses 50-cloud-init.conf) so
+# the cloud-init file takes precedence
+cat << EOF >> "/etc/ssh/sshd_config.d/60-cloudimg-settings.conf"
 PasswordAuthentication no
 EOF