[e2e_testing] check process exitcode early in e2e (#3591)

It will exit immediately. So it doesn't need to wait 6 min.

projects/pt1/python/torch_mlir_e2e_test/framework.py

@@ -395,7 +395,14 @@ def run_tests(
 
     pool = mp.Pool(num_processes)
     arg_list = zip(tests, repeat(config))
+    pool_copy = pool._pool[:]
     handles = pool.starmap_async(compile_and_run_test, arg_list)
+    while not handles.ready():
+        if any(proc.exitcode for proc in pool_copy):
+            print("At least one of testing processes has exited with code != 0.")
+            exit(1)
+        handles.wait(timeout=1)
+    else:
         results = handles.get(timeout=360)
 
     tests_with_results = {result.unique_name for result in results}