Bluetooth: samples: Use bt_gatt_find_by_uuid in peripheral sample
Bluetooth: samples: Use bt_gatt_find_by_uuid in peripheral sample

Demonstrate use of bt_gatt_find_by_uuid in peripheral sample. This
avoids the magical array index.

Signed-off-by: Joakim Andersson <cf0fcab5d38d6e132e92a97bcb0bae257abf4936@nordicsemi.no>

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