[Core] Deprecating block manager v1 and make block manager v2 default (#8704)

Removing the block manager v1. This is the initial piece of prefix-caching-centric design. In order to achieve prefix-caching-centric design, we need to simplify the code path so that we only use v2 block manager (which has much higher performance on prefix caching).

tests/spec_decode/e2e/test_integration.py

@@ -12,8 +12,6 @@ MAIN_MODEL = "JackFram/llama-68m"
 @pytest.mark.parametrize(
     "common_llm_kwargs",
     [{
-        # Required for spec decode.
-        "use_v2_block_manager": True,
 
         # Verify equality when cuda graphs allowed.
         "enforce_eager": False,
@@ -57,9 +55,6 @@ def test_spec_decode_cuda_graph(vllm_runner, common_llm_kwargs,
 
         # Skip cuda graph recording for fast test.
         "enforce_eager": True,
-
-        # Required for spec decode.
-        "use_v2_block_manager": True,
     }])
 @pytest.mark.parametrize("per_test_common_llm_kwargs", [
     {
@@ -111,9 +106,6 @@ def test_speculative_model_quantization_config(vllm_runner, common_llm_kwargs,
 
         # Skip cuda graph recording for fast test.
         "enforce_eager": True,
-
-        # Required for spec decode.
-        "use_v2_block_manager": True,
         "speculative_model": "JackFram/llama-68m",
         "num_speculative_tokens": 3,
     }])