Resolve the bug without encode batch flag when send batch message

[jonnxu]

What is the purpose of the change

Resolve the issue for send batch message

Brief changelog

Resolve the bug when send batch message without encode batch flag in SendMessageRequestHeader

Verifying this change

SendResult: sendStatus:0,msgId:010011AC0000F15A000082BE6D0F0200,offsetMsgId:0BC1F01E00002A9F0000022B24C575D4,queueOffset:5467,transactionId:,messageQueue:MessageQueue [topic=MQ_INST_*************_BaoCMwkE%t-common-message, brokerName=qd5internet-01, queueId=1]

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[ShannonDing]

LGTM