Fix instance-wide actor webfinger lookup

This skips the silenced-user check.

Ref T820

webfinger.go

@@ -43,6 +43,9 @@ func (wfr wfResolver) FindUser(username string, host, requestHost string, r []we
 		log.Error("Unable to get blog: %v", err)
 		return nil, err
 	}
+	c.hostName = wfr.cfg.App.Host
+
+	if !c.IsInstanceColl() {
 		silenced, err := wfr.db.IsUserSilenced(c.OwnerID)
 		if err != nil {
 			log.Error("webfinger find user: check is silenced: %v", err)
@@ -51,7 +54,7 @@ func (wfr wfResolver) FindUser(username string, host, requestHost string, r []we
 		if silenced {
 			return nil, wfUserNotFoundErr
 		}
-	c.hostName = wfr.cfg.App.Host
+	}
 	if wfr.cfg.App.SingleUser {
 		// Ensure handle matches user-chosen one on single-user blogs
 		if username != c.Alias {