This change include the show load of loadv2 and some bug fix of loadv2.
Firstly, the show load will perform both load and loadv2 info. According to loadv2, the ETL progress of loadv2 is N/A during the period of loading.
Secondly, the loadv2 will be created when version of property is v2.
This is a temporary property which will not influence the old broker load.
After the loadv2 is finished, the default load will be changed to loadv2.
Finally, there are some bug in LoadingTaskPlanner fixed by this change.
77a1b31baa