Simplify NSSAI configuration in all configuration files

...iles/episci/episci_gnb.band78.sa.fr1.106PRB.usrpn310.conf

...files/episci/proxy_gnb.band78.sa.fr1.106PRB.usrpn310.conf

ci-scripts/conf_files/gNB_SA_CU.conf

ci-scripts/conf_files/gNB_SA_DU.conf

ci-scripts/conf_files/gNB_SA_n78_106PRB.2x2_usrpn310.conf

ci-scripts/conf_files/gNB_SA_n78_133PRB.2x2_usrpn310.conf

...onf_files/gnb.band78.sa.fr1.106PRB.2x2.usrpn310.asue.conf

...pts/conf_files/gnb.band78.sa.fr1.106PRB.2x2.usrpn310.conf

...nf_files/gnb.band78.sa.fr1.106PRB.ddsuu.2x2.usrpn310.conf

ci-scripts/conf_files/gnb.band78.sa.fr1.106PRB.usrpn310.conf

...pts/conf_files/gnb.band78.sa.fr1.162PRB.2x2.usrpn310.conf

ci-scripts/conf_files/gnb.sa.band66.fr1.106PRB.usrpn300.conf

ci-scripts/conf_files/gnb.sa.band78.fr1.106PRB.usrpb210.conf

ci-scripts/conf_files/gnb.sa.band78.fr1.24PRB.usrpb210.conf

doc/TESTING_5GSA_setup.md

targets/PROJECTS/GENERIC-NR-5GC/CONF/cu_gnb.conf

targets/PROJECTS/GENERIC-NR-5GC/CONF/du_gnb.conf

...-NR-5GC/CONF/gnb.band78.tm1.106PRB.usrpn300.gtp-itti.conf

...ENERIC-NR-5GC/CONF/gnb.sa.band41.fr1.106PRB.usrpb210.conf

...ENERIC-NR-5GC/CONF/gnb.sa.band66.fr1.106PRB.usrpn300.conf