Don't use neutral evidences when scoring progress

**Describe the bug**
When generating a progress score, the AI is currently using all evidences. Evidences that are `neutral` should not be considered in the scoring.

This is giving a false sense of progress when there is none. We don't show neutral evidences in the UI, so we shouldn't consider it in the scoring.

Alternatively, is there any strong reason why we are attaching neutral evidences in the first place?

Example with neutral evidences that should not be considered in the progress scoring: https://outcomes-tracker-api.apps.canadasbuilding.com/admin/resources/promises/207

No files or tests are named. Start by tracing the progress-score generation entry point and how evidences with a neutral status are passed into scoring; confirm the behavior against the linked promise example. Done means neutral evidences no longer affect progress scores, with coverage for that case if the project has relevant tests.

Written by the indexing model from the issue text.