Geomap: Unify Marker Sizing

In marker layers in Geomap, there are inconsistencies in how different markers are sized. Before [webGL was introduced](https://github.com/grafana/grafana/pull/95457), square, circle, triangle, cross, x-mark, plane, and star were all generated using different methods: vector generation of polygons, lines, or direct vector graphic sources. In some cases markers are generated to be exactly the size specified in pixels, and in other cases, much larger. With webGL, there are 3 `WebGLRegularShapes`: square, circle, triangle; and the rest are vector graphics sourced. As far as I can tell, WYSIWYG in terms of size; however, to help ease migration pains, it was decided to introduce a scalar to the sizing to "split the difference" between the old implementation and new. We figured that worst case scenario, markers will be larger than a user expects causing a slight annoyance that can easily be resolved, whereas markers that are too small might lead to the user not being able to see critical information. Read more about the it [here](https://github.com/grafana/grafana/pull/95457#issuecomment-2704626984). [markerComparison.pdf](https://github.com/user-attachments/files/19116692/markerComparison.pdf) The scope of this issue is to unify the sizing for all markers with a well defined relationship between size and bounding box pixels.