Fix wrong plate y possition after switching profiles with different bed size

[Noisyfox]

There is a long lasting bug that sometimes when you open existing projects with >= 3 build plates, sometimes every models on plate other than the first row get shifted down, especially when you have multiple printer profiles with different plate size:

Notice that, in the first image, the gaps between plates are rectangles:

However once you switched between profiles that have different bed size, the gaps changed to squares, as shown in image 2:

The vertical spacing changes after swithing profiles, this includes opening 3mf files that has a different plate size than current profile, which causes everything get shifted.

This PR fixes this issue.

Please be aware, that the square gap is the correct behavior! The vertical gaps should have never been greater than the horizental gaps (which was a bug introduced in version 1.6.2). This means after this fix, all existing projects saved from version 1.6.2+ that have more than 2 plates will have the model shifted down (or up, depends on whether you switched the printer profile before saving), which is unfortunate but a necessary pain.

Fix #4016
Fix #7917

The fix is cherrypicked from BBS, thanks!

[yomarcyo]

@Noisyfox thanks for taking care (I'm the one who reopened this issue). As I have no idea if the above is good, bad or nothing at all (I literally created an account on GitHub to file this issue), just one question: Is there anything I can do?

Again, thank you so much for taking care. I always thought: Why participate? Everyone will give less of a s**t. But apparently that's not the case and someone is actually looking into it.

Best,
Marc