tests/arm_ramfunc: Disable picolibc heap for this test
tests/arm_ramfunc: Disable picolibc heap for this test

This leaves an MPU partition free for this test

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

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