[Bug]: Custom report charts scrollability with a long legend

### Verified issue does not already exist?

- [x] I have searched and found no existing issue

### What happened?

If you create a "split by category" custom report chart as part of a budget with lots of categories, then display the legend/summary on the right hand side, the chart itself will stretch its height to match the height of the right side panel instead of the screen itself.

Ideally you'd only need to scroll the legend panel if there are lots of items. At the moment, viewing the chart like this is quite unwieldy.

### How can we reproduce the issue?

- Create a budget with transactions using plenty of categories (30+ does it for me, depending on your window size)
- Create a custom report:
- stacked bar graph or line graph
- split by category
- include as many categories as you can (long timespan, no filters, etc.)
- show legend and summary
- The bar chart won't stretch to fill the screen anymore, it will stretch to fill the vertical space used by the long legend. So you'll need to keep scrolling up and down the chart to view the contents.

### Where are you hosting Actual?

Pikapods

### What browsers are you seeing the problem on?

Firefox

### Operating System

Linux