Allow multi-core building of mongo-cxx-driver dependency

[Bckempa]

The mongo driver in the space_robots_demo container is always built with a single core and has become a major bottleneck in our test cycle.

[EzraBrooks]

It's worth noting that we can just exclude the package that depends on this (moveit's warehouse system) from Space ROS if we want - it's not super actively developed.