Fix double-E1 bearer context setup req in E1 handler

If two PDU sessions are to be setup, the CU-CP sends two bearer context
setup requests. When running only the CU-UP, we inconditionally tried to
set up the CU-UP UE ID identifiers upon reception of the bearer context
setup request, leading to an assert. Check if the IDs are not already
set up, to avoid assertions in that case.

openair2/LAYER2/nr_pdcp/cucp_cuup_handler.c

@@ -149,7 +149,7 @@ void e1_bearer_context_setup(const e1ap_bearer_setup_req_t *req)
   /* mirror the CU-CP UE ID for CU-UP */
   uint32_t cu_up_ue_id = req->gNB_cu_cp_ue_id;
   f1_ue_data_t ued = {.secondary_ue = req->gNB_cu_cp_ue_id};
-  if (need_ue_id_mgmt) {
+  if (need_ue_id_mgmt && !cu_exists_f1_ue_data(cu_up_ue_id)) {
     bool success = cu_add_f1_ue_data(cu_up_ue_id, &ued);
     DevAssert(success);
     LOG_I(E1AP, "adding UE with CU-CP UE ID %d and CU-UP UE ID %d\n", req->gNB_cu_cp_ue_id, cu_up_ue_id);