configs: Update Arm simple configs to enable --interactive option

Removed the calls to `sys.exit()` from the Arm simple configs. These
calls terminate gem5's embedded Python interpreter and gem5 at the end
of the config script, preventing gem5 from dropping into the
interactive IPython shell when the `--interactive` option has been
specified.

Change-Id: I0c350b0d107f297691255361d25c566c889f9469
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/69687
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>

configs/example/arm/starter_fs.py

@@ -194,11 +194,9 @@ def run(args):
             m5.checkpoint(os.path.join(cpt_dir))
             print("Checkpoint done.")
         else:
-            print(exit_msg, " @ ", m5.curTick())
+            print(f"{exit_msg} ({event.getCode()}) @ {m5.curTick()}")
             break
 
-    sys.exit(event.getCode())
-
 
 def main():
     parser = argparse.ArgumentParser(epilog=__doc__)