retiolum check-free-retiolum-v4: update ipv4 addr

This is a no-op, but it looks nicer than some more random address.
retiolum install: pass full IPv4 to check-free-retiolum-v4

This fixes a bug, where an unused address (10.243.0.10) could not be
used another address (10.9.0.10) has the same suffix.