5.65: Edge of an uncropped edge asset pack does not match the edge of P1 side on a `type_b` thumbnail

[Wolfy76700]

When selecting the type_b thumbnail template and using assets without any uncropped edges (e.g. sg/full), the edge sometimes will not match the edge of the P1 side when it does. Using the default backgrounds, this results in 1-pixel wide red column appearing in the middle of the image

Example

Used game settings

[joaorb64]

We should probably round stuff up when it's on the right side and down when it's on the left side