test: wallet: BnB marks exhaustive search complete #36775

SelectCoinsBnB marks its result as completed when it exhausts the search space before reaching TOTAL_TRIES. Only the incomplete case is checked in the unit tests (bnb_exhaustion_with_solution_test), and the bnb_finds_min_waste fuzz target only reads the flag to decide whether to assert optimality, so reporting false goes unnoticed.

This PR checks GetAlgoCompleted() in TestBnBSuccess for cases that finish below the attempt limit (100,000).

Kills the following mutant (https://mutanthub.space/mutants/1096):

--- a/src/wallet/coinselection.cpp
+++ b/src/wallet/coinselection.cpp
@@ -233,7 +233,7 @@ util::Result<SelectionResult> SelectCoinsBnB(std::vector<OutputGroup>& utxo_pool
             if (curr_selection.empty()) {
                 // Exhausted search space before running into attempt limit
                 is_done = true;
-                result.SetAlgoCompleted(true);
+                result.SetAlgoCompleted(false);
                 break;
             }
             // Set `next_utxo` to one after last selected, then deselect last selected UTXO

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External sites

• Code coverage & benchmarks: https://corecheck.dev/bitcoin/bitcoin/pulls/36775
• Ralph review <img src=https://review.fish.foo/assets/bitcoin/bitcoin/36775.png alt="Ralph review status"> https://git.fish.foo/bitcoin/bitcoin/pulls/36775#author-ralph

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ACK ac2c946d3b211e90abb48357b0cb2afadbc64a38

Some people find such small PRs not worth responding to but I think small PRs are fine, especially if people are just learning their way around.

crACK https://github.com/bitcoin/bitcoin/commit/ac2c946d3b211e90abb48357b0cb2afadbc64a38

ACK ac2c946d3b211e90abb48357b0cb2afadbc64a38

Not strictly related to this PR, but is the reason for CI failure here likely to have been github service related? (https://github.com/bitcoin/bitcoin/actions/runs/42030338160/job/127515412961)

Not strictly related to this PR, but is the reason for CI failure here likely to have been github service related?

I don't think it is a service issue, a service problem would usually show timeouts or 5xx errors. The error says couldn't find remote ref and I found similar CI fail at #36658 (https://github.com/bitcoin/bitcoin/actions/runs/40365464333/job/121792086648)

Post merge ACK