Merge remote-tracking branch 'origin/cuup-load-tester' into integration_2025_w32 (!3547)

Add a CU-UP load tester and improve GTP performance

This adds a simple tester program for the CU-UP. It sets up a number of
UEs/bearers in the CU-UP via the E1 interface, then streams data in
downlink/uplink (as seen by the CU-UP). More information is available in
tests/nr-cuup/README.md.

Includes some fixes to properly verify that SCTP is installed, and use
"the right cmake way" to use it in cmake code (see commit for details).

common/ran_context.h

@@ -46,7 +46,6 @@ struct gNB_RRC_INST_s;
 struct eNB_MAC_INST_s;
 struct eNB_MAC_INST_NB_IoT_s;
 struct gNB_MAC_INST_s;
-struct gtpv1u_data_s;
 struct RU_t_s;
 
 typedef struct {
@@ -100,8 +99,6 @@ typedef struct {
   struct eNB_MAC_INST_NB_IoT_s **nb_iot_mac;
   /// NR MAC context variables
   struct gNB_MAC_INST_s **nrmac;
-  /// GTPu descriptor 
-  struct gtpv1u_data_s *gtpv1u_data_g;
   /// RU descriptors. These describe what each radio unit is supposed to do and contain the necessary functions for fronthaul interfaces
   struct RU_t_s **ru;
   /// Mask to indicate fronthaul setup status of RU (hard-limit to 64 RUs)