aggressively resource constrain baloo_file

baloo_file is a very particular background service in that it has the potential to eat all the user's CPU and IO time. To prevent this from practically ever happening we'll lower the respective weight controls way down and further constrain memory consumption to make it incredibly unlikely that we baloo may be the case of OOM scenarios.

this means baloo still gets as much CPU/IO time as it wants, but not ever at the cost of another cgroup.

I've been running these constraints for well over a year and noticed no negative effects.