[1/N][Attention] Restructure attention: move files (#31916)

Signed-off-by: Matthew Bonanni <mbonanni@redhat.com>

tests/compile/fullgraph/test_full_graph.py

@@ -10,10 +10,10 @@ import torch
 
 from tests.quantization.utils import is_quant_method_supported
 from vllm import LLM, SamplingParams
-from vllm.attention.backends.registry import AttentionBackendEnum
 from vllm.config import CompilationConfig, CompilationMode, CUDAGraphMode, PassConfig
 from vllm.platforms import current_platform
 from vllm.utils.torch_utils import is_torch_equal_or_newer
+from vllm.v1.attention.backends.registry import AttentionBackendEnum
 
 from ...utils import create_new_process_for_each_test