CI: Configuration file adjustment for NSA-B200-Module-LTEBOX-Container

Try to reduce number of false RA attempts on eNB

ci-scripts/conf_files/enb.nsa.band7.25prb.usrpb200.conf

@@ -215,6 +215,7 @@ L1s =
 (
   {
     num_cc = 1;
+    prach_dtx_threshold = 200;
     tr_n_preference = "local_mac";
   }
 );