Move the check_max_open_files into loop_interval.

Since check_max_open_files has no bearing on wether we accept the minion or not, there is no reason to list the directory on every auth call. With this mechanism it is a "fixed cost" since it will run at loop_interval instead of on each auth call
Merge pull request #9376 from jacksontj/develop

Move the check_max_open_files into loop_interval.