[bug]: `lncli listpayments --count_total_payments` should not return a copy of all payments, instead it should return only the total

[ZZiigguurraatt]

Right now because of #8530 we can use

lncli listpayments --count_total_payments --max_payments 2|jq .total_num_payments

to count the total number of payments without receiving a copy of them all. However, once #8530 is fixed, we won't have a way to count the total with large databases because of #9709 .

I think we should change lncli listpayments --count_total_payments to not return a copy of all payments, instead it should return only the total.

What does everyone else think?

#9740 aims to fix #9717 and it is designed to only return the total, not a copy of the invoices too. I'm thinking that is the better approach and should work in the same way with listpayments.