tests: net: wifi: Disable native/64 from tests

There are issues with 64 bit compilation in hostap so disable
native_sim/native/64 board from the tests. The board will be
enabled again after updating the hostap from upstream and fixing
the issues.

Fixes #80437

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