Remove superfluous "channel" in comment (#21887)

Automatic Merge

store/sqlstore/channel_store.go

@@ -577,7 +577,7 @@ func (s SqlChannelStore) upsertPublicChannelT(transaction *sqlxTxWrapper, channe
 	return nil
 }
 
-// Save writes the (non-direct) channel channel to the database.
+// Save writes the (non-direct) channel to the database.
 func (s SqlChannelStore) Save(channel *model.Channel, maxChannelsPerTeam int64) (_ *model.Channel, err error) {
 	if channel.DeleteAt != 0 {
 		return nil, store.NewErrInvalidInput("Channel", "DeleteAt", channel.DeleteAt)