[IOTDB-4222] Create data region repeatedly when concurrently deleting and creating storage groups

[HeimingZ]

Synchronize ready condition rather than MNode. Besides, StorageEngineV2 doesn‘t have this problem.

[ericpai]

@HeimingZ Are there any other code blocks that should be changed as well? If one code uses synchronized keyword, then there must be at least another one.

[HeimingZ]

@HeimingZ Are there any other code blocks that should be changed as well? If one code uses synchronized keyword, then there must be at least another one.

@ericpai Just block here is ok, this method is the only interface to get data region. For example, when two threads hold different MNode to get the same data region, they will block at the same ready condition.

[ericpai]

@HeimingZ Are there any other code blocks that should be changed as well? If one code uses synchronized keyword, then there must be at least another one.

@ericpai Just block here is ok, this method is the only interface to get data region. For example, when two threads hold different MNode to get the same data region, they will block at the same ready condition.

Thanks. LGTM!