Library path wrong for subsites (4.x)

There's a config in the module to override this path already. The current patch unfortunately doesn't work if an absolute URL has been entered. And it also won't work if the base path has been manually prefixed already.

I think we need to additionally check two things first:

1. 1. Is the URL relative and has the base path already been entered
2. 2. Is it an external URL

In both cases the base path should not be added.

The failing pipeline is unrelated to this issue and has already been addressed in 🐛 LazyForm too few arguments Needs review .