revid: don't append Config.RTMPURL

Config.RTMPURL was being appended when updated, which means that
it would just continue to grow, and by the time we actually try
to use the RTMP URLs that are stored, we end up using old ones.
Instead this should just be completely replaced.

revid/config/variables.go

@@ -586,10 +586,7 @@ var Variables = []struct {
 		Type: typeString,
 		Update: func(c *Config, v string) {
 			v = strings.ReplaceAll(v, " ", "")
-			split := strings.Split(v, ",")
-			for _, s := range split {
-				c.RTMPURL = append(c.RTMPURL, s)
-			}
+			c.RTMPURL = strings.Split(v, ",")
 		},
 	},
 	{