Verification of continuous ingest with agitation should check for orphaned files

Original Jira ticket: [ACCUMULO-4748](https://issues.apache.org/jira/browse/ACCUMULO-4748)

We have found instances where files are being orphaned but we have not as of writing this ticket figured out why. We should however expand the continuous ingest verification to check for orphaned files which we hypothesize will show up when agitation is when running continuous ingest.

Start by locating the continuous ingest verification and its agitation-related test or entry point in the repository. Run the existing verification to understand how orphaned files would be observed, then define the check and test conditions with the maintainers. Done means the verification reliably reports orphaned files during agitation.

Written by the indexing model from the issue text.