1. Modify the binlog reader to stop reading a fixed 4096 rows and
instead use the calculated bufferSize to avoid generating small binlogs.
2. Use a fixed bufferSize (32MB) for the Parquet reader to prevent OOM.
issue: https://github.com/milvus-io/milvus/issues/43387
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Signed-off-by: bigsheeper <yihao.dai@zilliz.com>