kconfig: default to LEGACY_INCLUDE_PATH=n
kconfig: default to LEGACY_INCLUDE_PATH=n

Change the default config for LEGACY_INCLUDE_PATH to 'n'.

This makes any test or sample fail CI if there's any #include missing
the "zephyr/" prefix.

Signed-off-by: Fabio Baltieri <1c55e39c05d9ab42261288cf330256b2af6ba179@google.com>

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