restore FThenB pp

Author: waliwali777

tests/test_tipc/static/auto_parallel/llama2/pretrain_config_llama2_13b/pretrain-llama2_13b_dynamic_auto.json

@@ -13,8 +13,8 @@
   "sharding_parallel_config": "enable_overlap enable_tensor_fusion",
   "tensor_parallel_config": "enable_mp_async_allreduce",
   "pipeline_parallel_config": "enable_send_recv_overlap enable_split_backward",
-  "pipeline_schedule_mode": "VPP", 
-  "virtual_pp_degree": 5,
+  "pipeline_schedule_mode": "FThenB", 
+  "virtual_pp_degree": 1,
   "sequence_parallel": 0,   
   "use_flash_attention": true,
   "use_fused_rms_norm": true,