For the L2Txs of TransferToEthAddr & TransferToBJJ for a not-yet
existing accounts, in the TxSelector check if L2Tx receiver account will
be created by a L1UserFrozenTxs (in the next batch, the current frozen
queue). In that case, the L2Tx will be discarded at the current batch,
even if there is an AccountCreationAuth for the account, as there is a
L1UserTx in the frozen queue that will create the receiver Account.  The
L2Tx is discarded to avoid the Coordinator creating a new
L1CoordinatorTx to create the receiver account, which will be also
created in the next batch from the L1UserFrozenTx, ending with the user
having 2 different accounts for the same TokenID.
The double account creation is supported by the Hermez zkRollup
specification, but it was decided to mitigate it at the TxSelector level
for the explained cases.