Thank you for the provided screenshot and StackBlitz example.
Basically we can change the height of the ComboBox popup, using the popupSettings property. Also, we can change the listHeight of the popup which affects only the list of suggestions and not the whole popup container.
Using the provided CSS styles, I am afraid that 10px height would not fit the content provided in the no data template.
Here is an example of a list with 10 px height applied without using any icons in the template, using custom CSS code: