ctdb-tests: Be more careful when building public IP addresses

ctdb-tests: Be more careful when building public IP addresses

The goal is to allow more local daemons by expanding the address range
rather than generating invalid addresses.

For IPv6, use a separate address space instead of an offset for the
2nd address.

For IPv4, use the last 2 octets with addresses starting at
192.168.100.1 and 192.168.200.1.  Avoid addresses with 0 and 255 in
the last octet by using a maximum of 100 addresses per "subnet"
starting at .1.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>