Set storage group and auto create timeseries failure causes unaccessible device（创建存储组与自动创建序列失败导致的无效device的创建）

[MarcosZyk]

IoTDB version 0.12.1
Test case:

1. set storage group to root.cj4.jr01;
2. insert into root.cj4.jr02.ing(timestamp,s1) values(2021,1);
3. set storage group to root.cj4.jr02;

After opetating the above operation in sequence, IoTDB will throw storageGroupAlreadyExsitException and root.cj4.jr02 can't be set as storage group.

[MarcosZyk]

1. auto create timeseries failure
The storageGroupAlreadyExsitException is caused by default_storage_group_level.
When auto creating timeseries root.cj4.jr02.ing.s1, IoTDB try to set a storage group for this timeseries and the target is root.cj4 because the default_storage_group_level is 1.
However, since root.cj4.jr01 has already been set to storage group, root.cj4 can't be set to storage group. IoTDB assumes that any device or timeseries works under some storage group, thus a node with children can't be set to storage group.

2. try set storage group manually failure
After auto creating timeseries root.cj4.jr02.ing.s1 failure, trying to set storage group to root.cj4.jr02 also fails.
That is because during auto creating timeseries, device root.cj4.jr02.ing is created without storage group ancestor or any timeseries descendant.
Only operation, set storage group to this node's descendant, can work on such node. IoTDB doesn't provide any modification operations on device and this makes users confusing about how to deal with a device without storage group ancestor or any timeseries descendant.

3. Solutions

1. Try use another storage group or device and leave the unaccessible device alone.
2. Set storage group to the device node's descendant and the path can be used again.
3. This bug has been fixed since IoTDB 0.12.2. Update IoTDB and redo the operations.