TEZ-1362. Remove DAG_COMPLETED in DAGEventType. (Jeff Zhang via hitesh)

(cherry picked from commit b9e1d39a01f7a6550029f01617f0cc35fd798eb0)
TEZ-1362. Remove DAG_COMPLETED in DAGEventType. (Jeff Zhang via hitesh)

(cherry picked from commit bfb7b5a87420856f209a67d367c4b4197fc32860)