SD-1051

There were other issues which creeped in while fixing this issue.

1. After fetching an item from ingest the item appeared twice in Ingest tab, this is because `_type` is being persisted to Mongo and the same was pushed to elastic as part of `source` attribute.
2. After fetching when the document is observed in `archive` collection the `version_creator` is `None`, which doesn't make sense. Reason being when celery task starts flask.g.user is unset.
3. While inserting the document into `archive_versions` attributes like `lock_user`, `lock_session`... which are irrelevant were being inserted into the collection. Modified `metadata_schema` to have `versioned=False` for irrelevant attributes.
I know, the thing is I'm not sure this is a good approach when using celery. We can keep this like this for now, maybe we can improve it later on.