Overriding autodetected NUMA node count.

[srdo]

A user ran into the case that humio_processes was autodetected to 16, which is too many for their host to handle.

Overriding that value is easy enough, but the underlying numanodes fact is also used for setting environment variables.

https://github.com/humio/ansible-server/search?q=numanodes

Maybe it would be easier for users to control if we had a variable in defaults/main for the ansible_local.numanodes array, so users could replace that as well?

[schofield]

This sounds like good approach.