MAINTAINERS: Move audio shell into Bluetooth audio
MAINTAINERS: Move audio shell into Bluetooth audio

The audio shell isn't really part of the core host.

Signed-off-by: Jonathan Rico <fa71e224653c2b3d230eecbd20dc417397790bdf@nordicsemi.no>

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