Configure indexSliceSize to 16MB (#17080)

Signed-off-by: Nzhenshan.cao <zhenshan.cao@zilliz.com>

configs/milvus.yaml

@@ -288,7 +288,7 @@ common:
   # Valid values: [auto, avx512, avx2, avx, sse4_2]
   # This configuration is only used by querynode and indexnode, it selects CPU instruction set for Searching and Index-building.
   simdType: auto
-  indexSliceSize: 4 # MB
+  indexSliceSize: 16 # MB
 
   # please adjust in embedded Milvus: local
   storageType: minio