fix #5461: pvecm: use ssh_info_to_command for intra cluster ssh

fix #5461: pvecm: use ssh_info_to_command for intra cluster ssh

because otherwise the SSH calls to other nodes in the cluster will fail
on newer clusters that only have the ssh host keys located in the
pmxcfs.

With ssh_info_to_command we get all the needed SSH options that set the
alias and point to the right known_hosts file.

Signed-off-by: Aaron Lauterer <a.lauterer@proxmox.com>