Check release validation counts without requiring order

internal/releasecheck/assets_test.go

@@ -256,9 +256,15 @@ func TestCandidateCheckerSelectsOwnedValidationOnce(t *testing.T) {
 		"off vet -mod=readonly ./...",
 		"off build-release-assets v1.2.3",
 	}
-	for index, prefix := range want {
-		if !strings.HasPrefix(lines[index], prefix) {
-			t.Fatalf("owned command %d = %q, want prefix %q", index, lines[index], prefix)
+	for _, prefix := range want {
+		count := 0
+		for _, line := range lines {
+			if strings.HasPrefix(line, prefix) {
+				count++
+			}
+		}
+		if count != 1 {
+			t.Fatalf("owned command %q ran %d times, want once: %q", prefix, count, lines)
 		}
 	}
 }