HDDS-12546. [DiskBalancer] Display bytesMoved instead of VolumeDensity in status output

[Gargi-jais11]

What changes were proposed in this pull request?

As VolumeDensity is already covered by report sub command, we will show bytesMoved (bytesBalanced) in status command.

Besides, the meaning of VolumeDensity is clear to end user, but the real value indicating is not that straight forward. Use the estimated pending move size(HDDS-12437) will help user to clearly understand how much data size need to move. And this bytesMoved is also a straight forward value, indicating the work disk balancer has done.

What is the link to the Apache JIRA

https://issues.apache.org/jira/browse/HDDS-12546

How was this patch tested?

Added unit test to test bytesToMoveMB, bytesMovedMB and calculateEstimatedTimeLeft to show reasonable values when bytesToMove and bytesMoved are less than 1MB.

As well as tested manually by running docker cluster locally.

bash-5.1$ ozone admin datanode diskbalancer status
Status result:
Datanode                            Status          Threshold(%)    BandwidthInMB   Threads      SuccessMove  FailureMove  BytesMoved(MB)  EstBytesToMove(MB) EstTimeLeft(min)
ozone-datanode-4.ozone_default      RUNNING         0.0002          10              5            5            3            7136            896             2              
ozone-datanode-3.ozone_default      RUNNING         0.0002          10              5            7            4            13131           3080            6              

Note: Estimated time left is calculated based on the estimated bytes to move and the configured disk bandwidth.

[ChenSammi]

Thanks @Gargi-jais11 .