fix(saturation): active_gitaly saturation message
What
- Remove the mention of the balancer.
- Remove mention of disk space of other nodes.
Why
- Balancer allows us to move repositories from one Gitaly node to another, but our % of available disk space stays the same so there is not much point to balance.
-
disk_space
on the nodes that are inactive (above 80%) don't count part of this saturation metric so we shouldn't mention them to make it less confusing.