ssh-agent unit file should cleanup after itself

install/etc/skel/.config/systemd/user/ssh-agent.service

@@ -4,6 +4,7 @@ Description=SSH key agent
 [Service]
 Type=simple
 Environment=SSH_AUTH_SOCK=%h/.ssh/socket
+ExecStartPre=/usr/bin/rm -f $SSH_AUTH_SOCK
 ExecStart=/usr/bin/ssh-agent -D -a $SSH_AUTH_SOCK
 
 [Install]