Fixes #5673 by connecting Xenoflora to the Xenobiology disposal section.

Xenobiology already had disposals going all the way into Xenoflora where they were suddenly cut off.
The last distance of pipes and disposal unit has be added.
Merge pull request #5674 from PsiOmegaDelta/Xenosposals

Fixes #5673 - Xenoflora disposals