samples: net: Disable native_posix target in more samples

The native_posix compilations fail with various socket
errors like this:

samples/net/sockets/can/src/main.c:65:9: error: implicit \
     declaration of function ‘send’ [-Werror=implicit-function-declaration]
     65 |   ret = send(fd, &sframe, sizeof(sframe), 0);
        |         ^~~~

So disable the native_posix board from networking samples as
native_posix board is not compatible with CONFIG_POSIX_API

This is related to commit b8fc1c4c ("samples: net: Disable
native_posix target in samples") but disables more network samples
for native_posix board.

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