wendelin: add big size data ingestion test
After SR: https://lab.nexedi.com/nexedi/slapos/-/merge_requests/1893
add test to check if we can ingest big data in wendelin, here in the test, we ingest ~6MB data
but since zope.conf is not used during ERP5 unit tests
we need to set manually in runUnitTest.py
Edited by Xiaowu Zhang