Lots that exist are skipped instead of updated during Lotman initialization

[jhiemstrawisc]

When Lotman init code runs, it creates a list of lots that need to exist based on the provided configuration. However, right now the InitLotman skips over lots that already exist without checking whether this should actually be an update to the underlying lot. This means that an administrator who wants to update something like a Lot's management policy attributes first needs to delete the lot by calling into the sql database and then restart the cache with the updated yaml configuration.

We can handle this in Pelican to decrease the headache for administrators by modifying these existence checks to also grab the lot and update it if there any of the values in the provided configuration don't match what's stored in the database.