Tree endpoint in data extractor is deprecated

[p-galligan]

Describe the bug

DataExtractor_ArchivesSpace.py uses a deprecated AS endpoint as of AS version 3.1.0.

Impact on your work

Cannot upgrade to AS 3.1.0 until this is updated

Additional context

Not sure what the best way to remediate this issue is. Extractor is grabbing the whole tree and setting it to a variable. Trees seem to be used in a few places here.

[helrond]

In VirtualVault, it looks like this method is not actually called, so we should be able to just get rid of that code and/or add a comment that indicates it's deprecated but uncalled in our environment.