dist: scylla_raid_setup: don't override XFS block size on modern kernels
In 6977064693 ("dist: scylla_raid_setup:
reduce xfs block size to 1k"), we reduced the XFS block size to 1k when
possible. This is because commitlog wants to write the smallest amount
of padding it can, and older Linux could only write a multiple of the
block size. Modern Linux [1] can O_DIRECT overwrite a range smaller than
a filesystem block.
However, this doesn't play well with some SSDs that have 512 byte
logical sector size and 4096 byte physical sector size - it causes them
to issue read-modify-writes.
To improve the situation, if we detect that the kernel is recent enough,
format the filesystem with its default block size, which should be optimal.
Note that commitlog will still issue sub-4k writes, which can translate
to RMW. There, we believe that the amplification is reduced since
sequential sub-physical-sector writes can be merged, and that the overhead
from commitlog space amplification is worse than the RMW overhead.
Tested on AWS i4i.large. fsqual report:
```
memory DMA alignment: 512
disk DMA alignment: 512
filesystem block size: 4096
context switch per write io (size-changing, append, blocksize 4096, iodepth 1): 0.0003 (GOOD)
context switch per write io (size-changing, append, blocksize 4096, iodepth 3): 0.7961 (BAD)
context switch per write io (size-unchanging, append, blocksize 4096, iodepth 3): 0 (GOOD)
context switch per write io (size-unchanging, append, blocksize 4096, iodepth 7): 0.0001 (GOOD)
context switch per write io (size-unchanging, append, blocksize 512, iodepth 1): 0.125 (BAD)
context switch per write io (size-unchanging, overwrite, blocksize 512, iodepth 1): 0 (GOOD)
context switch per write io (size-unchanging, overwrite, blocksize 512, O_DSYNC, iodepth 1): 0 (GOOD)
context switch per write io (size-unchanging, overwrite, blocksize 512, O_DSYNC, iodepth 3): 0 (GOOD)
context switch per write io (size-unchanging, overwrite, blocksize 512, O_DSYNC, iodepth 3): 0 (GOOD)
context switch per write io (size-changing, append, blocksize 4096, iodepth 1): 0 (GOOD)
context switch per write io (size-changing, append, blocksize 4096, iodepth 3): 0.8006 (BAD)
context switch per write io (size-unchanging, append, blocksize 4096, iodepth 3): 0.0001 (GOOD)
context switch per write io (size-unchanging, append, blocksize 4096, iodepth 7): 0 (GOOD)
context switch per write io (size-unchanging, append, blocksize 512, iodepth 1): 0.125 (BAD)
context switch per write io (size-unchanging, overwrite, blocksize 512, iodepth 1): 0 (GOOD)
context switch per write io (size-unchanging, overwrite, blocksize 512, O_DSYNC, iodepth 1): 0 (GOOD)
context switch per write io (size-unchanging, overwrite, blocksize 512, O_DSYNC, iodepth 3): 0 (GOOD)
context switch per read io (size-changing, append, blocksize 512, iodepth 30): 0 (GOOD)
```
The sub-block overwrite cases are GOOD.
In comparison, the fsqual report for 1k (similar):
```
memory DMA alignment: 512
disk DMA alignment: 512
filesystem block size: 1024
context switch per write io (size-changing, append, blocksize 1024, iodepth 1): 0.0005 (GOOD)
context switch per write io (size-changing, append, blocksize 1024, iodepth 3): 0.7948 (BAD)
context switch per write io (size-unchanging, append, blocksize 1024, iodepth 3): 0.0015 (GOOD)
context switch per write io (size-unchanging, append, blocksize 1024, iodepth 7): 0.0022 (GOOD)
context switch per write io (size-unchanging, append, blocksize 512, iodepth 1): 0.4999 (BAD)
context switch per write io (size-unchanging, overwrite, blocksize 512, iodepth 1): 0 (GOOD)
context switch per write io (size-unchanging, overwrite, blocksize 512, O_DSYNC, iodepth 1): 0 (GOOD)
context switch per write io (size-unchanging, overwrite, blocksize 512, O_DSYNC, iodepth 3): 0 (GOOD)
context switch per write io (size-unchanging, overwrite, blocksize 512, O_DSYNC, iodepth 3): 0 (GOOD)
context switch per write io (size-changing, append, blocksize 1024, iodepth 1): 0 (GOOD)
context switch per write io (size-changing, append, blocksize 1024, iodepth 3): 0.798 (BAD)
context switch per write io (size-unchanging, append, blocksize 1024, iodepth 3): 0.0012 (GOOD)
context switch per write io (size-unchanging, append, blocksize 1024, iodepth 7): 0.0019 (GOOD)
context switch per write io (size-unchanging, append, blocksize 512, iodepth 1): 0.5 (BAD)
context switch per write io (size-unchanging, overwrite, blocksize 512, iodepth 1): 0 (GOOD)
context switch per write io (size-unchanging, overwrite, blocksize 512, O_DSYNC, iodepth 1): 0 (GOOD)
context switch per write io (size-unchanging, overwrite, blocksize 512, O_DSYNC, iodepth 3): 0 (GOOD)
context switch per read io (size-changing, append, blocksize 512, iodepth 30): 0 (GOOD)
```
Fixes #25441.
[1] ed1128c2d0
Closes scylladb/scylladb#25445
5d1846d783