Optimize street level imagery zoom level and colours

[danieldegroot2]

I feel like I have to zoom in somewhat far to load Bing Streetside imagery. Mapillary loads fine on lower zoom levels. KartaView loads in chunks (regardless of zoom). Though seems to be tied to API limits mostly.

I also think the dark blue points from Mapilio are a bit too dark and cluttering for the editor's style (regardless of zoom). The editor could use soft colours here, even if the branding colour differs. Currently the white ring starts to be slightly distracting.

Ref #5482 (regarding performance)