Exception print in sendDefaultImpl function in DefaultMQProducerImpl.

[talen0702]

在DefaultMQProducerImpl的sendDefaultImpl这个方法中，如果出现RemotingException或MQClientException异常，会打印信息，但异常信息是一样的，也没有特别的逻辑，是否可以合成一个或打印信息加以区分，会更容易理解，谢谢

[ShannonDing]

A PR can be submit to print the log separately with different context or print them together.

[zhiliatom]

The same question exists in the class DefaultMQProducerImpl at line 898~915

[RongtongJin]

Merged