CI: Run CATs without parallelism in fresh and windows
CI: Run CATs without parallelism in fresh and windows

* BBL 8.4.91 with the cheaper/more modern VM sizes is out.
* We're seeing some more CATS failures on runs with high parallelism
  almost definitely due to the Diego Cells being much less powerful (4
  cores => 2 cores).
* This is being investigated, but in the meantime we should cut down on
  parallelism in CATs with these two environments that use the new BBL.
  They may take a long time to run now but at least they might pass.

cloudfoundry/cf-deployment,cloudfoundry/cf-deployment