Atomize the metrics models and APIs
https://redmine.teklia.com/issues/2483#change-55343
- Remove the
MetricKeyandMetricValuemodels - Move the
MetricModeenum to thetraining.0001migration - Remove the
CreateMetricValueandCreateMetricValuesendpoints
You may need to update the test fixtures since they include some Django permissions, even though we don't use those.