Rocket crawlers get stuck delivering to a full pad that is not theirs

Issue description

crawler is from the left side assembly, intended to service the left side launch, however two things happen here;

• left crawler takes from left assembly to right pad, and vice-versa for the right sided crawler
• crawlers will latch themselves to delivering to a specific pad even if its full and another has been empty for months

first point isnt necessarilly an issue, so long as the required pads are fulfilled for necessary cargo deliveries
second point creates the problem in combination with the first; you end up with one pad that needs a critical delivery to be made, but none of the assemblies are able to provide a rocket to do so

if a wall is built between the left and right side both sides stop working entirely, regardless of where each of the crawlers are, they get stuck in a loop trying to path-find to both pads simultaneously

another third point; you cant assign fixed routes between assemblies and pads, nor can assemblies and pads be fixed to zones, the crawlers themselves can be assigned to zones, but this is not functionally implemented and has zero effect

https://1drv.ms/u/c/918dc61a06cb8df9/EX_M9OBx2v9MpgqQYNRAN-YBi39pJ6Fo0dW21gInsq6Mew?e=Psy5J8

Reproduction steps

Game version and build number

0.7.7 b470

Operating system

Windows

Rockets already prefer empty launchpads; there could be some race condition where both rockets were built at the same time. Not sure as I cannot reproduce it there. We also added support so that rocket transporters recognize logistics zones. Assigning routes would be nice, but that's currently out of scope.