Revert "disable caching in kv_manager to fix second identical request failed error"

This reverts commit 5702cc8.

Author: bukeao

vllm/v1/core/kv_cache_manager.py

@@ -68,7 +68,7 @@ def __init__(
         self,
         kv_cache_config: KVCacheConfig,
         max_model_len: int,
-        enable_caching: bool = False,
+        enable_caching: bool = True,
         caching_hash_algo: str = "builtin",
         use_eagle: bool = False,
         log_stats: bool = False,