bluetooth: tests: Improve bondable_per_connection bsim test

Added fail on pairing_failed callback for both central and peripheral.
Added pairing status checks in peripheral.

It has been done to test the case when multi-role BT device tried to
pair without bonding (peripheral role) while already previously bonded
with the same device on another Bluetooth identity as it seems that
there was an issue with it previously.

Signed-off-by: Mateusz Kapala <mateusz.kapala@nordicsemi.no>