Activating and deactivating harvest definitions takes a long time

Activating or deactivating a large harvest definitions takes way too long a time: for instance it takes 2:30 minutes on a harvest definition with about 3,300 configs.

This is due to the fact that that Definitions-selective-harvests.jsp makes a call to HarvestDefinitionDAO#getHarvestDefinition(String) which reads a hierarchy of thousands of objects ifrom the DB.

We should instead use the SparsePartialHarvest object and a single request to see if there are configs.

Note: we should also implement some type of object cache for the full definitions, but this should be done in a separate improvement issue.