wallet: Replace nFeeRateNeeded with effective_fee
wallet: Replace nFeeRateNeeded with effective_fee

Make sure that all fee calculations use the same feerate.
coin_selection_params.effective_fee is the variable we use for all fee
calculations, so get rid of remaining nFeeRateNeeded usages and just
directly set coin_selection_params.effective_fee.

Does not change behavior.

Github-Pull: #21083
Rebased-From: e2f429e6bbf7098f278c0247b954ecd3ba53cf37

litecoin-project/litecoin,litecoin-project/litecoin,litecoin-project/litecoin,qtumproject/qtum,litecoin-project/litecoin,rnicoll/dogecoin,rnicoll/dogecoin,litecoin-project/litecoin,qtumproject/qtum,qtumproject/qtum,qtumproject/qtum,rnicoll/dogecoin,rnicoll/dogecoin,rnicoll/dogecoin,litecoin-project/litecoin,qtumproject/qtum,qtumproject/qtum,qtumproject/qtum