tests/cbprintf: Use minimal libc to test cbprintf code
tests/cbprintf: Use minimal libc to test cbprintf code

These tests all assume that the same underlying cbprintf function will be
used for all operations, which is not true when using picolibc. Force the
use of the minimal C library as that will check the right code paths.

Signed-off-by: Keith Packard <fd7f967895e9f35e58ec8a62a847a54d7fa7275f@keithp.com>

galak/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,galak/zephyr