[bugfix][main]KV Pool for KV Transfer in PD Disaggregation Scenarios (#5398)

### What this PR does / why we need it?
1.KV Pool for KV Transfer in PD Disaggregation Scenarios Error
Resolution
2.Update KV Pool Documentation

### Does this PR introduce _any_ user-facing change?

### How was this patch tested?

- vLLM version: release/v0.13.0
- vLLM main:
254f6b9867

---------

Signed-off-by: fems14 <1804143737@qq.com>

vllm_ascend/distributed/kvpool/ascend_store_connector.py

@@ -55,7 +55,7 @@ class AscendStoreConnector(KVConnectorBase_V1):
             )
 
             assert self.connector_worker is not None
-            if vllm_config.parallel_config.rank == 0 and self.kv_role != "kv_consumer":
+            if vllm_config.parallel_config.rank == 0:
                 self.lookup_server = LookupKeyServer(self.connector_worker,
                                                      vllm_config,
                                                      self.use_layerwise)