Implement all fragment instance of one query in one dataNode sharing dop

[Alima777]

Before, every fragment instance can enjoy the dop of system even though they belong to the same query. However, if we have 5 data regions and 5 fragment instances are allocated to one dataNode, they will use 5 * dop which is not our expectation. There, I Implement all fragment instance of one query in one dataNode sharing dop.