Switch to DiscountCT by Feb 2025

[dangeross]

See https://discord.com/channels/547454030801272832/656789435869954048/1319074210856964187

[roeierez]

This explains the discount size for confidential transactions very well: https://github.com/ElementsProject/ELIPs/blob/main/elip-0200.mediawiki

We should also update our rust-elements crate to include the latest changes regarding the weight calculation for discounted transaction.
We also need to upgrade our liquid node to be able to relay such transactions

[roeierez]

We have the new liquid node that supports this deployed.
It seems now we need to:

1. update our client to include the code for calculating the discounted size.
2. Calculate the right fees accordingly and make sure when we use blockstream public node to broadcast the transaction it is minded and the swapper accepts it in zero conf swaps.