Fix DistributedDoubleBarrier enter and leave methods because using the same watcher affects each other

[nailsoul]

Scenario: QTY clients call the enter method, QTY-1 clients call the leave method, the number of clients is not enough so it blocks, and the working directory leaves the smallest node. At this time, the smallest node client receives the notification that the ready node is created to wake up the thread , it is checked that only one node deletes the node, and other clients are woken up Solution: use different watchers for enter and leaver methods Test case: TestDistributedDoubleBarrier.testEnterAffectLeaveByWatcher