[FS-11674] Use systemd native RunAs User

debian/freeswitch-systemd.freeswitch.service

@@ -10,15 +10,17 @@ After=network.target network-online.target local-fs.target
 ; service
 Type=forking
 PIDFile=/run/freeswitch/freeswitch.pid
-Environment="DAEMON_OPTS=-nonat"
+Environment="DAEMON_OPTS=-ncwait -nonat"
+Environment="USER=freeswitch"
+Environment="GROUP=freeswitch"
 EnvironmentFile=-/etc/default/freeswitch
-ExecStartPre=/bin/chown -R freeswitch:freeswitch /var/lib/freeswitch /var/log/freeswitch /etc/freeswitch /usr/share/freeswitch /var/run/freeswitch
-ExecStart=/usr/bin/freeswitch -u freeswitch -g freeswitch -ncwait $DAEMON_OPTS
+ExecStartPre=/bin/chown -R ${USER}:${GROUP} /var/lib/freeswitch /var/log/freeswitch /etc/freeswitch /usr/share/freeswitch /var/run/freeswitch
+ExecStart=/usr/bin/freeswitch ${DAEMON_OPTS}
 TimeoutSec=45s
 Restart=always
 ; exec
-User=root
-Group=daemon
+User=${USER}
+Group=${GROUP}
 LimitCORE=infinity
 LimitNOFILE=100000
 LimitNPROC=60000