RocketMQ fix metadata properties

[shubham1172]

Problem

There are some unused and wrongly implemented metadata in RocketMQ.

Metadata	Issue	Possible resolution
AccessProto	unused	Add or remove it
GroupName	misguiding	Should be renamed to ProducerGroupName
ConsumerBatchSize	unused	Add or remove it
SendTimeOut	incorrect implementation	Instead of nanoseconds, use milliseconds or seconds.

Release Note

RELEASE NOTE: FIX RocketMQ metadata properties

[artursouza]

LGTM

[helbing]

/assign