integration fix: fix crash

With value 4 when connecting one UE and doing some downlink
iperf TCP there is a crash. Probably due to the multiple wrong
RA detected leading to uplink failure of fake UE that never
sends Msg3 (because, well, there is no other UE).

This is another problem that will be fixed at some point.

Anyway, this value 4 fails. Let's put back 3.