This PR introduces a parallelism limit during garbage collection. This
is used to avoid large resource usage spikes if garbage collecting many
allocations at once.
This PR:
* Makes AWS network speeds more granular
* Makes `network_speed` an override and not a default
* Adds a default of 1000 MBits if no network link speed is detected.
Fixes#1985
I apologize in advance for the rather long PR, but unfortunately there
is not an easy way to break this up into smaller chunks. This separates
the agent configuration into smaller, more consumable pieces just like
the job specification.
Diptanu Choudhury