vdk-oracle: further load testing

[DeltaMichael]

Overview

Load testing done here is not the worst case scenario #2907 (comment)

The worst case scenario would be something like this test (variable payload), but on a much larger scale, e.g. 1 000 000 objects with a randomized subset of keys.

https://github.com/vmware/versatile-data-kit/blob/main/projects/vdk-plugins/vdk-oracle/tests/jobs/oracle-ingest-job-different-payloads-no-table/10_ingest.py

Acceptance criteria

1. Do the load testing (can be done ad-hoc using a functional test)
2. Report results in this ticket

Follow-up

#2931