CU-CP/UP: release UE at PDCP in CU-CP

We reuse RRC UE IDs at the RRC. Previous to this commit, we did not
release a UE at the CU-CP's PDCP (for SRBs). Thus, when reconnecting a
UE, the PDCP might not be in a good state, since we did not release the
previous PDCP UE context.

openair2/RRC/NR/rrc_gNB.c

@@ -1904,6 +1904,10 @@ static void rrc_CU_process_ue_context_release_complete(MessageDef *msg_p)
   }
   gNB_RRC_UE_t *UE = &ue_context_p->ue_context;
 
+  /* we call nr_pdcp_remove_UE() in the handler of E1 bearer release, but if we
+   * are in E1, we also need to free the UE in the CU-CP, so call it twice to
+   * cover all cases */
+  nr_pdcp_remove_UE(UE->rrc_ue_id);
   rrc_gNB_send_NGAP_UE_CONTEXT_RELEASE_COMPLETE(instance, UE->rrc_ue_id);
   LOG_I(NR_RRC, "removed UE CU UE ID %u/RNTI %04x \n", UE->rrc_ue_id, UE->rnti);
   rrc_delete_ue_data(UE);