Update S3 keys for Archivematica payloads

Why these changes are being introduced:

Preservation stakeholders have requested that new ETD SIPs (generated
via APT) remain separate from legacy SIPs. This helps make their
Archivematica workflows more efficient.

Relevant ticket(s):

* [ETD-669](https://mitlibraries.atlassian.net/browse/ETD-669)

How this addresses that need:

This changes the base directory for Archivematica payload S3 keys from
`etdsip` to `etdsip-apt`.

Side effects of this change:

We will need to re-preserve the batch of theses that were published
yesterday.

Author: jazairi

app/models/archivematica_payload.rb

@@ -82,7 +82,7 @@ def bag_name
 
   # The bag_output_uri key is constructed to match the expected format for Archivematica.
   def bag_output_uri
-    key = "etdsip/#{thesis.graduation_year}/#{thesis.graduation_month}-#{thesis.accession_number}/#{bag_name}.zip"
+    key = "etdsip-apt/#{thesis.graduation_year}/#{thesis.graduation_month}-#{thesis.accession_number}/#{bag_name}.zip"
     [ENV.fetch('APT_S3_BUCKET'), key].join('/')
   end