Revert "Change hardcoded task id to TASK_VARIABLE"

executables/nr-softmodem.c

openair2/F1AP/f1ap_cu_interface_management.c

openair2/LAYER2/PDCP_v10.1.0/pdcp.c

openair2/LAYER2/nr_pdcp/nr_pdcp_oai_api.c

openair2/RRC/LTE/rrc_eNB.c

openair2/RRC/LTE/rrc_eNB_GTPV1U.c

openair2/RRC/NR/rrc_gNB.c

openair2/RRC/NR/rrc_gNB_NGAP.c

openair2/SIMULATION/NR_RRC/itti_sim.c

openair3/GTPV1-U/gtpv1u_eNB.c

openair3/GTPV1-U/gtpv1u_gNB.c

openair3/GTPV1-U/gtpv1u_task.c

openair3/GTPV1-U/nw-gtpv1u/src/NwGtpv1u.c

targets/COMMON/create_tasks.c

targets/COMMON/create_tasks_mbms.c