[Bugfix][KV Offload] Bound unaligned SWA loads by physical GPU blocks (#49052)

Signed-off-by: Colton Ottley <colton@ottleyengineering.com>
Co-authored-by: Colton Ottley <colton@ottleyengineering.com>
Co-authored-by: jasl <jasl9187@hotmail.com>
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
Co-authored-by: Or Ozeri <oro@il.ibm.com>

vllm/distributed/kv_transfer/kv_connector/v1/offloading/scheduler.py

@@ -860,6 +860,7 @@ class OffloadingConnectorScheduler:
                     num_pending_gpu_blocks
                     <= group_config.sliding_window_size_in_chunks
                     * self.config.blocks_per_chunk
+                    + 1
                 )
 
             num_chunks = cdiv(num_cached_tokens, tokens_per_chunk)