test: wallet: BnB incomplete result on attempt-limit success #35590

BnB can return a valid selection before exhausting the search tree, then hit TOTAL_TRIES while continuing to look for a better one. Add a unit test for that path using a known exhaustion fixture plus an exact-match coin, and assert the result is marked incomplete via GetAlgoCompleted() == false.

It kills the following mutant:

diff --git a/src/wallet/coinselection.cpp b/src/wallet/coinselection.cpp
index 8d69957c30..e4d07415f3 100644
--- a/src/wallet/coinselection.cpp
+++ b/src/wallet/coinselection.cpp
@@ -212,7 +212,7 @@ util::Result<SelectionResult> SelectCoinsBnB(std::vector<OutputGroup>& utxo_pool
 
         if (curr_try >= TOTAL_TRIES) {
             // Solution is not guaranteed to be optimal if `curr_try` hit TOTAL_TRIES
-            result.SetAlgoCompleted(false);
+            result.SetAlgoCompleted(true);
             break;
         }
 

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Code Coverage & Benchmarks

For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/35590.

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Conflicts

No conflicts as of last run.

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cc @murchandamus