Set scroll line count

Using the "editor.mouseWheelScrollSensitivity" setting.
(Go to settings and type in "scroll" to find the setting).

A value of:

• 0.45 will give you 1 line
• 0.9 will give you 2 lines
• 1.35 will give you 3 lines
• and so on...

You should be able to adjust that using this setting:

// A multiplier to be used on the `deltaX` and `deltaY` of mouse wheel scroll 
   events
"editor.mouseWheelScrollSensitivity": 1

Being a multiplier for example setting it to 2, you will double the scroll. But I don't know to be honest if you can use decimals. So for example putting 0.5 you should be able to have half of the scroll you have by default.

I hope it helps