lnwallet: don't add trimmed HTLC value to initiator commitment fees
lnwallet: don't add trimmed HTLC value to initiator commitment fees

This commit fixes a lingering bug in the way the internal channel state
machine handled fee calculation. Previously, we would count the dust
HTLC’s that were trimmed towards the fee that the initiator paid. This
is invalid as otherwise, the initiator would always benefit from dust
HTLC’s. Instead, we now simply “donate” the dust HTLC’s to the miner in
the commitment transaction. This change puts us in compliance with
BOLT-0003.

LightningNetwork/lnd,ddustin/lnd,ddustin/lnd,aakselrod/lnd,AndrewSamokhvalov/lnd,LightningNetwork/lnd,AndrewSamokhvalov/lnd,aakselrod/lnd