Print full child output for all tests in parallel mode

Always print each test's captured output, not just for failures.
This preserves backward compatibility:
- PASS appears on its own line per test, as before
- ASAN/UBSAN reports from any test appear in captured logs
- timeit output is preserved for all tests

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/test/api.cpp

@@ -160,7 +160,7 @@ void test_optimize_translate() {
     Z3_del_context(ctx1);
 }
 
-void test_max_reg() {
+void test_max_reg() {    
     // BNH multi-objective optimization problem using Z3 Optimize C API.
     // Mimics /tmp/bnh_z3.py: two objectives over a constrained 2D domain.
     //   f1 = 4*x1^2 + 4*x2^2