Clear Collection History Retention Settings when converting from Magma to Couchstore

We provide a simple one-step, annotations-based solution to migrate from Couchstore to Magma - this should work in reverse, but will be blocked if any Collections have history enabled.

As part of the annotations processing for Magma to Couchstore, we should clear any History Retention related settings that would block the reverse migration, rather than letting it fail, if we don't believe that History Retention is in use.

Only if both historyRetentionBytes and historyRetentionSeconds are still zero (i.e. history retention is not currently enabled), set history to false on any Collection where history is true, before attempting to set storageBackend.