## What changed?
I added support for correctness tests for our DLQ admin commands.
While here I added two tests for `tdbg dlq list` that _should_ have
caught the bug I fixed in #5744
## Why?
We had zero correctness tests before this, only tests for our error
handling.
## How did you test it?
I added new tests, of course!
## Potential risks
None
## Documentation
None
## Is hotfix candidate?
No