[core][executor] simplify instance id (#10976)

Signed-off-by: youkaichao <youkaichao@gmail.com>

vllm/envs.py

@@ -8,7 +8,6 @@ if TYPE_CHECKING:
     VLLM_RPC_BASE_PATH: str = tempfile.gettempdir()
     VLLM_USE_MODELSCOPE: bool = False
     VLLM_RINGBUFFER_WARNING_INTERVAL: int = 60
-    VLLM_INSTANCE_ID: Optional[str] = None
     VLLM_NCCL_SO_PATH: Optional[str] = None
     LD_LIBRARY_PATH: Optional[str] = None
     VLLM_USE_TRITON_FLASH_ATTN: bool = False
@@ -175,11 +174,6 @@ environment_variables: Dict[str, Callable[[], Any]] = {
     "VLLM_USE_MODELSCOPE":
     lambda: os.environ.get("VLLM_USE_MODELSCOPE", "False").lower() == "true",
 
-    # Instance id represents an instance of the VLLM. All processes in the same
-    # instance should have the same instance id.
-    "VLLM_INSTANCE_ID":
-    lambda: os.environ.get("VLLM_INSTANCE_ID", None),
-
     # Interval in seconds to log a warning message when the ring buffer is full
     "VLLM_RINGBUFFER_WARNING_INTERVAL":
     lambda: int(os.environ.get("VLLM_RINGBUFFER_WARNING_INTERVAL", "60")),