[Sim, Pdr bot] In sim and pdr bot tests, need to test both classifier _and_ regressor ai models

[trentmc]

Background / motivation

In sim engine tests: there's currently an end-to-end test for classifier. Same for sim plot and for pdr bot tests.

We recently added regression ai models. They're mostly the same to use as classifiers; but there are differences.

We've encountered at least one bug in pdr bot because it couldn't properly handle regression models.

Let's robust-ify our code.

TODOs / DoD

• Pre-requisite: #1209 "Write basic end-to-end tests for sim plots & arima plots"
• In sim plot tests: ensure there's an end-to-end test for both classifier and regressor
• In sim engine tests: ""
• In pdr bot tests: ""