[main] remove dbo code (#3712)

### What this PR does / why we need it?
Remove codes of dbo.
Currently, vLLM has supported dbo with pr:
https://github.com/vllm-project/vllm/pull/23693.

### Does this PR introduce _any_ user-facing change?

### How was this patch tested?

- vLLM version: v0.11.0rc3
- vLLM main:
17c540a993

Signed-off-by: zzzzwwjj <1183291235@qq.com>

vllm_ascend/envs.py

@@ -82,9 +82,6 @@ env_variables: Dict[str, Callable[[], Any]] = {
     "VLLM_ENABLE_FUSED_EXPERTS_ALLGATHER_EP":
     lambda: bool(int(os.getenv("VLLM_ENABLE_FUSED_EXPERTS_ALLGATHER_EP", '0'))
                  ),
-    # Whether to enable DBO feature for deepseek model.
-    "VLLM_ASCEND_ENABLE_DBO":
-    lambda: bool(int(os.getenv("VLLM_ASCEND_ENABLE_DBO", '0'))),
     # Whether to enable the model execute time observe profile. Disable it when
     # running vllm ascend in production environment.
     "VLLM_ASCEND_MODEL_EXECUTE_TIME_OBSERVE":