Query plan visualizer shows total instead of self for Buffer Hits

[FranckPachot]

Describe the bug

The Tree View has an option to show the node's values (Self) instead of cumulative (Total) but it doesn't work for all metrics.

Buffer Hits Self:

They show the cumulative total. Should be like Buffers - node's self value

[erdemtuna]

Thanks for the report Franck Pachot (@FranckPachot), we'll look into this!