test_python_export failures with affine coordinates

[dhomeier]

Some of these tests have always failed with self.viewer_load('affine') ever since those coords were first added in

No idea if those AffineCoordinates make any sense at all, but they work – apart from the _slice and simple_att tests, that suffer from some fuzziness in the (lower axis) labels. Looks like the exported version does not get the 3D look quite right – can probably live with that?

Originally posted by @dhomeier in glue-viz/glue#2335 (comment)

As of Astropy 7.0 those failures have shown up in 6 more tests, all in the same way mismatching just on the abscissa labels, and now xfailed as well in f349d72. Arguably the plots from the exported script (top image) are actually looking more correct, with matching font sizes, though I originally suspected that the larger fonts were somehow intended to create more of a "3D" look.

[astrofrog]

I recently moved over some of the Python export tests to glue-core and fixed them in the process. We should actually remove them from here.

[dhomeier]

For all viewers? They are all covered by glue-viz/glue#2524, but those originally marked xfail still are off.
Locally I also have test_subset_transposed['affine'] failing with Astropy 7 on some missing minor ticks, but don't see that in CI.
So should I purge all 5 tests in #26?