Fix CI test for FR2 RA

ci-scripts/conf_files/gnb.band261.tm1.32PRB.usrpn300.conf

@@ -225,6 +225,7 @@ RUs = (
          att_tx         = 0;
          att_rx         = 0;
          bands          = [7];
+         sl_ahead       = 12;
          max_pdschReferenceSignalPower = -27;
          max_rxgain                    = 75;
          eNB_instances  = [0];