CASSANDRA-19104 Standardize tablestats formatting and data units

[zaaath]

Standardizes space and memory formatting in nodetool tablestats human-readable output.

Before

Nodetool tablestats returns a mix of "bytes", "KiB/MiB/GiB", or no units at all.
Example:

        Space used (live): 1463210998523 bytes
        Space used (total): 1463210998523 bytes
        Space used by snapshots (total): 0
        Off heap memory used (total): 607419608 bytes
...
        Memtable data size: 248539982 bytes
        Memtable off heap memory used: 0 bytes
...
        Bytes repaired: 0.000KiB
        Bytes unrepaired: 4315.386GiB
        Bytes pending repair: 0.000KiB
...
        Bloom filter space used: 33590024 bytes
        Bloom filter off heap memory used: 33532560 bytes
        Index summary off heap memory used: 8174024 bytes
        Compression metadata off heap memory used: 565713024 bytes
        Compacted partition minimum bytes: 36
        Compacted partition maximum bytes: 17797419593
        Compacted partition mean bytes: 189740

After

Nodetool tablestats formats space and memory numbers using KiB/MiB/GiB units.
Example:

        Space used (live): 1.33 TiB
        Space used (total): 1.33 TiB
        Space used by snapshots (total): 0 bytes
        Off heap memory used (total): 579.28 MiB
...
        Memtable data size: 237.03 MiB
        Memtable off heap memory used: 0 bytes
...
        Bytes repaired: 0 bytes
        Bytes unrepaired: 4.21 TiB
        Bytes pending repair: 0 bytes
...
        Bloom filter space used: 32.03 MiB
        Bloom filter off heap memory used: 31.98 MiB
        Index summary off heap memory used: 7.8 MiB
        Compression metadata off heap memory used: 539.51 MiB
        Compacted partition minimum bytes: 36 bytes
        Compacted partition maximum bytes: 16.58 GiB
        Compacted partition mean bytes: 185.29 KiB

How to reproduce

nodetool tablestats -H

Tests

ant testsome -Dtest.name=org.apache.cassandra.utils.FBUtilitiesTest
ant testsome -Dtest.name=org.apache.cassandra.tools.nodetool.stats.TableStatsPrinterTest
ant testsome -Dtest.name=org.apache.cassandra.tools.nodetool.TableStatsTest

patch by @zaaath; reviewed by @smiklosovic for CASSANDRA-19104

[bschoening]

Using the existing stringifyFileSize seems like the right approach.

[zaaath]

@bschoening thanks, I totally agree that using the existing stringifyFileSize method is the right approach.