rtx: fix advertising RTX support in disco
rtx: fix advertising RTX support in disco

damencho/lib-jitsi-meet,jitsi/lib-jitsi-meet,nevermind-corp/ljm,adambowles/lib-jitsi-meet,adambowles/lib-jitsi-meet,jitsi/lib-jitsi-meet,jiyeyuran/lib-jitsi-meet