Conflict with the CRC token used to compensate the relayer for the tx type HubTransfer

[llunaCreixent]

In this line (https://github.com/CirclesUBI/circles-core/blob/main/src/utils.js#L800) a token among the CRC tokens the sender holds is used to compensate the relayer. However, this same token might be necessary for fulfilling the transfer steps in the HubTransfer. This issue is only relevant for HubTransfers and not for the rest of operations (trust, addOwner, etc.).

explore: if we transfer all the balance of a token that was supposed to be used for paying the relayer for the tx gas, would it generate an error?