[Perf][ROCm] Use hipMemcpyBatchAsync in swap_blocks_batch#41737

Etelis wants to merge 3 commits into

vllm-project:mainvllm-project/vllm:mainfrom

Etelis:rocm-swap-blocks-batchEtelis/vllm:rocm-swap-blocks-batchCopy head branch name to clipboard