[refactor] refactor model runner capture model (#5230)

### What this PR does / why we need it?
Refactor the `capture_model` method in model_runner to directly reuse
the method from vLLM.

Currently, most of the logic in the capture_model method is similar to
that in the vllm code. Directly using the vllm method can reduce the
maintenance cost of the vllm-ascend code. Modify as follows:
1、refactor capture_model function, directly inheriting community methods
2、refactor initialize_aclgraph_capture function, move to
initialize_attn_backend

### Does this PR introduce _any_ user-facing change?
No

### How was this patch tested?

- vLLM version: release/v0.13.0
- vLLM main:
ad32e3e19c

Signed-off-by: weiguihua2 <weiguihua2@huawei.com>
Co-authored-by: weijinqian0 <1184188277@qq.com>

vllm_ascend/platform.py

@@ -26,6 +26,8 @@ from vllm.platforms import Platform, PlatformEnum
 
 # todo: please remove it when solve cuda hard code in vllm
 os.environ["VLLM_DISABLE_SHARED_EXPERTS_STREAM"] = "1"
+# todo: please remove it when support controls garbage collection during CUDA graph capture.
+os.environ["VLLM_ENABLE_CUDAGRAPH_GC"] = "1"
 
 from vllm_ascend.ascend_config import init_ascend_config
 from vllm_ascend.utils import refresh_block_size
@@ -244,6 +246,12 @@ class NPUPlatform(Platform):
                 data_parallel_size,
             )
             compilation_config.use_inductor = False
+            # NOTE: Theoretically, we should also add vllm::mla_forward in the attention ops.
+            # Since the process is created in the spawn mode, the value of the class attribute
+            # attention ops transmitted is still the one before modification, so it has not been modified.
+            # This will cause in scenarios where both piecewise and splitting ops are configured simultaneously,
+            # If splitting ops does not contain the vllm::mla forward value, this configuration issue will
+            # not be detected in advance assert.
             compilation_config.splitting_ops.extend(["vllm::mla_forward"])
             update_aclgraph_sizes(vllm_config)
             ascend_config.enable_npugraph_ex = False