Default Collector Values

[gabrieleiannetti]

The default collector values are set all to extended which will enable for the collector.mdt the processing of the MDTChangelogUsers. This will throw an error on non Lustre MDS machines (see issue).

TODOs:

• Change all default values for collector types e.g. core, this should suppress the above error in the current architecture, since all core metrics are read from files and not via lctl as with extended mdt metrics.
• Update documentation, so it is clear which are the default values.