fix leafcloud keyfile to match workflow

Author: sjpb

environments/.stackhpc/LEAFCLOUD.pkrvars.hcl

@@ -6,6 +6,6 @@ networks = ["909e49e8-6911-473a-bf88-0495ca63853c"] # slurmapp-ci
 source_image_name = "openhpc-230804-1754-80b8d714" # https://github.com/stackhpc/ansible-slurm-appliance/pull/298
 fatimage_source_image_name = "Rocky-8-GenericCloud-Base-8.9-20231119.0.x86_64.qcow2"
 ssh_keypair_name = "slurm-app-ci"
-ssh_private_key_file = "~/.ssh/id_ed25519"
+ssh_private_key_file = "~/.ssh/id_rsa"
 security_groups = ["default", "SSH"]
 floating_ip_network = "external"