Fix automatedRoadConnectionPath serialization errors

[yairm210]

Somehow the custom serialization worked for everything except for within lists, which looks like it uses its own nonsense.
So we're rolling back this change, and temporarily disabling the saving of the list (MapUnit.automatedRoadConnectionPath) to allow games to continue normally
Resolves #12095

[yairm210]

release patch

[SomeTroglodyte]

worked for everything except for within lists

I mentioned something similar in the past few weeks somewhere... This behaves possibly quite different between setSerializer and implements Serializable - but these hooks both are not the first tests in Gdx's decision tree. For example, ClassReflection.isAssignableFrom(Collection.class, type) absolutely moronically trumps both classToSerializer and Serializable - Json.java line 998.

... which seems exactly what we ran into here. Only solution is to ensure containers aren't recognizable as Java Collection or have their own hook. Or avoid Gdx. Or fork Gdx and fix that idiocy.

Sorry I didn't remember and warn earlier.