The dhclient package is creating its .leases files in /var as part of its post
script
(https://build.opensuse.org/package/view_file/network:dhcp/dhcp/dhcp.spec?expand=1,
currently lines 444-447). This does not work with transactional-update, as /var
is not accessible during updates.
In this case this may be quite hypothetical, as dhclient will probably always
be installed during the initial installation anyway, but the files are still
cluttering up the root file system.

Creating the files sounds like a classical case for systemd-tmpfiles (if it's
still necessary to manually create the files at all, maybe the lines can simply
be deleted?).