hanges swift xfs inode advice to be more modern

In past couple of years, the XFS team has greatly improved inode use in
xfs. With more recent kernels, there is no performance penalty for
using the default inode size, and a smaller inode size gives us
improvements in other areas where disk access is involved.

fixes bug 1196768

Change-Id: Ib5903bffc6e113155b40d5df63919f4ca5c6ed73
Remove Costs from the 'Weights and Costs' Chapter

Costs are no longer used in the scheduler, so Weights chapter is
updated with the remaining ram_weight_multiplier option.

Fixes bug 1172264

Change-Id: Ic8c57b2107c1e334acb1adfe3498d33fde7b435d
Merge "Remove Costs from the 'Weights and Costs' Chapter"
Merge "hanges swift xfs inode advice to be more modern"