[Refactor] Remove Unused Environment Variable `VLLM_NO_DEPRECATION_WARNING` (#22199)

Signed-off-by: yewentao256 <zhyanwentao@126.com>

vllm/envs.py

@@ -70,7 +70,6 @@ if TYPE_CHECKING:
     NVCC_THREADS: Optional[str] = None
     VLLM_USE_PRECOMPILED: bool = False
     VLLM_TEST_USE_PRECOMPILED_NIGHTLY_WHEEL: bool = False
-    VLLM_NO_DEPRECATION_WARNING: bool = False
     VLLM_KEEP_ALIVE_ON_ENGINE_DEATH: bool = False
     CMAKE_BUILD_TYPE: Optional[str] = None
     VERBOSE: bool = False
@@ -582,10 +581,6 @@ environment_variables: dict[str, Callable[[], Any]] = {
     lambda: bool(
         int(os.getenv("VLLM_ENABLE_FUSED_MOE_ACTIVATION_CHUNKING", "1"))),
 
-    # If set, vllm will skip the deprecation warnings.
-    "VLLM_NO_DEPRECATION_WARNING":
-    lambda: bool(int(os.getenv("VLLM_NO_DEPRECATION_WARNING", "0"))),
-
     # If set, the OpenAI API server will stay alive even after the underlying
     # AsyncLLMEngine errors and stops serving requests
     "VLLM_KEEP_ALIVE_ON_ENGINE_DEATH":