tests: net: shell: Increase number of IP address structs

A warning is printed in start of the test about this.
Increase CONFIG_NET_IF_MAX_IPV6_COUNT=2 and
CONFIG_NET_IF_MAX_IPV4_COUNT=2 so that the tests pass
in frdm_k64f and some other boards.

Fixes #66020

Signed-off-by: Jukka Rissanen <jukka.rissanen@nordicsemi.no>