[FIX] iot: bluetooth work with serial

Using path such as '/dev/ttyUSB0' to connect to a serial port
makes it impossible to use the bluetooth.

We now use the locations in '/dev/serial/by-path' to connect to serial port,
which does not affect bluetooth connections

closes odoo/odoo#35302

Signed-off-by: Quentin Lejeune (qle) <qle@odoo.com>