`node_pixelate` sets the output pixel size to 1, meaning no
transformation occurs and it is essentially the same as a single value
input. This will add a new test that pixelates the image, and renames
the original test to better reflect that edge case
Coverage:
- Function: 62.50% -> 100%
- Line: 37.36% -> 100%
- Region: 45.83% -> 100%
- Branch: 20.00% -> 90.00%
Pull Request: https://projects.blender.org/blender/blender/pulls/142438
903fefff48