ipsec: T3643: bugfix on wrong destination file path for x509 key file
ipsec: T3643: bugfix on wrong destination file path for x509 key file

Commit a6b526fd982 ("ipsec: T3643: us vyos.util.copy_file() over raw UNIX cp
command") used a new helper to copy the x509 certificate files, but it also
added a bug where the certificate key file was copied to the wrong location.

This has been fixed and the corect path is used again.

vyos/vyos-1x,vyos/vyos-1x,vyos/vyos-1x,vyos/vyos-1x