spring cleaning: incorrect images in visual tests

[timtreis]

• [x] Image 1 (fixed by https://github.com/scverse/spatialdata-plot/pull/287) ~Background is taken as shape, should be white. White dots should probably be C~ https://github.com/scverse/spatialdata-plot/pull/323 and https://github.com/scverse/spatialdata-plot/pull/334

• [ ] Image 2 ~Probably same as image 1~

• [ ] Image 3 Why is bg black? Not black on local, only on runner?

• [ ] Image 4 Why is bg black? Not black on local, only on runner?

• [ ] Image 5 Why are some of the colors different? Non-deterministic return order of colors?

• [ ] Image 6 ~Did we change the default color? Why is legend gone?~ https://github.com/scverse/spatialdata-plot/pull/344

• [ ] Image 7 Why is there an extra triangle? Filter not working?

Image 8 Why are there two extra triangles?

Image 9 ~MultiPolygon broken~ https://github.com/scverse/spatialdata-plot/pull/334, extent broken (https://github.com/scverse/spatialdata/issues/693)