Bluetooth: Mesh: Remove usage of auto name in AD

The advertiser options to automatically add the name in the scan
response and the advertising data will be deprecated.

The Mesh files `proxy_srv.c` and `pb_gatt_srv.c` were using
BT_LE_ADV_OPT_USE_NAME. Add the device name in the advertising data
directly.

Signed-off-by: Théo Battrel <theo.battrel@nordicsemi.no>