VizTooltips: Improve maxHeight and positioning logic

### What happened? Trying out NewVizTooltips... I have a tooltip with a lot of items, some of which are now no longer visible:  ### What did you expect to happen? All items visible:  ### Did this work before? While I understand you can click and then scroll, and there does need to be a cut of limit at the number of items that that starts happening at, it would be nice if that limit was configurable. It also looks like the font size or spacing has increased so now the items take up more space. Again would be awesome to be able to configure this. ### How do we reproduce it? Add lots of items and enable "all" tooltips. ### Is the bug inside a dashboard panel? _No response_ ### Environment (with versions)? Grafana v11.1.0-170067 (81fd8f4126) ### Grafana platform? Docker ### Datasource(s)? _No response_