Change to candle trade for librarian villagers

In 26.1 snapshot 11, a replacement trade was introduced for master level librarian villagers, that has them sell red and yellow candles for at a rate of 3 emeralds > 1 candle. 

Instead of this, a better trade would be to randomize candles and have the villager trade regular candles, plus 2 random colours of candles for a rate of 2 emeralds > 3 candles.

- 3 candles specifically because collecting honeycomb from a beehive/nest gives 3 items.

- 2 emeralds because it comes out to 1.5 emeralds/candle, which feels fair, while also giving a potential for discounts.

- Randomized colours for the candle so that all candle types are renewable through this trade, instead of only red and yellow candles.