Ensure the CU-CP only sets up PDU sessions that are not already
established for the UE, skipping duplicates while keeping the NG UE
context valid. This aligns with 3GPP TS 38.413 PDU Session setup
semantics for duplicate session IDs
Changes:
- Change rrc_gNB_process_NGAP_INITIAL_CONTEXT_SETUP_REQ to scan requested
PDU sessions and detect IDs that already exist in UE->pduSessions with
PDU_SESSION_STATUS_ESTABLISHED
- Log a warning and skip already established PDU session IDs so they are
not added to UE->initial_pdus
- Collect only non-established PDU sessions into a temporary stack array,
allocate UE->initial_pdus with the exact count, copy them in, update
UE->n_initial_pdu, and only refresh UE AMBR when there is at least one
session to set up