scheduler locking bugfix

Creating `BasicLock` object on every scheduler run instead of reusing same object throughout.

Having same `BasicLock` object had one `claimId` being used in every lock acquisition that caused problem when 2 nodes tried to get lock at same time. Because of the way Cass deletes rows, inserting row with same `claimId` that was deleted earlier just enables the earlier row. And selecting ordered rows returns older row first causing the confusion.