Reuse the traversal key path in TestFilter's precomputed filter

TestFilter's precomputed filter receives each node's key path from the graph traversal but discards it and reconstructs the same value via `item.test.id.keyPathRepresentation` — re-allocating a [String] and re-formatting the source location to a string per node. Since the graph is built by inserting each test at `test.id.keyPathRepresentation`, the node's key path *is* that value, so use it directly.

Simpler, and removes a per-node allocation + string format from the filtering path. (~3.7x on the isolated per-node membership check; absolute per-run cost is sub-ms — this is a readability cleanup first.)

Author: inju2403

Sources/Testing/Running/Configuration.TestFilter.swift

@@ -283,18 +283,18 @@ extension Configuration.TestFilter.Operation {
     case let .precomputed(selection, membership):
       switch membership {
       case .including:
-        return testGraph.mapValues { _, item in
+        return testGraph.mapValues { keyPath, item in
           guard let item else {
             return nil
           }
-          return selection.contains(item.test) ? item : nil
+          return selection.contains(keyPath) ? item : nil
         }
       case .excluding:
-        return testGraph.mapValues { _, item in
+        return testGraph.mapValues { keyPath, item in
           guard let item else {
             return nil
           }
-          return !selection.contains(item.test, inferAncestors: false) ? item : nil
+          return !selection.contains(keyPath, inferAncestors: false) ? item : nil
         }
       }
     case let .function(function, membership):