Improve pending proofs tests

[thesimplekid]

These tests can be improved by selecting specific proofs to melt then using melt_proofs and then attempting to reuse the specefic selected proofs. This would ensure that it is know that the correct proofs are being tested for state. Currently the Memory database is used and there is only the one operation so pending proofs are related to the attempted melt, but if being specific would still be better. This would also allow better checking of fee used.

cdk/crates/cdk-integration-tests/tests/fake_wallet.rs

Lines 47 to 51 in 5139c47

	let melt = wallet.melt(&melt_quote.id).await;
	assert!(melt.is_err());
	attempt_to_swap_pending(&wallet).await?;