Rebalance failed in the second step while updating replica from 0 > 1 > 2.

Steps to reproduce

1. Create a 4 node cluster and a default bucket with replica=0

   +----------------+----------+--------------+

   | Nodes | Services | Status |

   +----------------+----------+--------------+

   | 172.23.105.220 | kv | Cluster node |

   | 172.23.105.221 | None | <--- IN --- |

   | 172.23.105.223 | None | <--- IN --- |

   | 172.23.105.225 | None | <--- IN --- |

   +----------------+----------+--------------+

2. Load 10M items in the bucket:

   2020-04-09 00:41:28,311 | test | INFO | MainThread | [table_view:display:72] Bucket statistics

   +---------+---------+----------+-----+---------+------------+------------+------------+

   | Bucket | Type | Replicas | TTL | Items | RAM Quota | RAM Used | Disk Used |

   +---------+---------+----------+-----+---------+------------+------------+------------+

   | default | membase | 0 | 0 | 10000000 | 7881097216 | 2143179672 | 2143007310 |

   +---------+---------+----------+-----+---------+------------+------------+------------+

3. Update replica to 1 and rebalance. Update all the items create earlier.
4. Update replica from 1 to 2 and rebalance and update all the items again in parallel.
5. Rebalance in the step above failed.

Rebalance exited with reason {mover_crashed,

{unexpected_exit,

{'EXIT',<0.2514.3>,

{{dcp_wait_for_data_move_failed,"default",

123,'ns_1@172.23.122.225',

['ns_1@172.23.122.208','ns_1@172.23.121.79'],

{error,no_stats_for_this_vbucket}},

[{ns_single_vbucket_mover,

'-wait_dcp_data_move/5-fun-0-',5,

[{file,"src/ns_single_vbucket_mover.erl"},

{line,465}]},

{proc_lib,init_p,3,

[{file,"proc_lib.erl"},{line,232}]}]}}}}.

Rebalance Operation Id = 455535458d4b34402d37b446165332a2