Fine Performance Metrics Dashboard nice-to-haves

- Part of #7665
- Follow-up to #7679

The new dashboard view for Fine Performance Metrics (#7725) could use some tweaking:

- [ ] Please add a plot for gather_dep (title: "Receive data, by activity"). It's not quite redundant with get_data, as for example it can highlight deserialization-specific issues.
- [ ] The bytes plot, as it is, is not very useful. The reason is that `memory-read` is going to eclipse everything else. The purpose of that metric is to compare it to disk-read and calculate cache hit ratios; nothing else. It would become instantly more useful if there was a filter by activity so that it can be excluded (just like the filter by prefix).

**EDIT: delivered in #7910**
- [x] The stacked bar charts could use a vertical axis
- [x] The pie charts could use an indication of percentage in the tooltip