The pair is similar to remote-fs.target and remote-fs-pre.target. Any
cryptsetup devices which require network shall be ordered after
remote-cryptsetup-pre.target and before remote-cryptsetup.target.
Normally this happens automatically, but if it happened that both targets were
pulled in, even though there were no cryptsetup units, they could be started
in reverse order, which would be somewhat confusing. Add an explicit ordering
to avoid this potential issue.