Externalise the high ISIS metric into oss-params

No need to change code when the high ISIS metric changes. It's part of the oss-params now.

As an added bonus, I've removed the example config in conftest.py as it now uses the example file instead. This also should help with keeping this example file up-to-date.

requested review from @Aleksandr.Kurbatov

assigned to @karel.vanklink

mentioned in merge request !168 (closed)

approved this merge request

thanks @karel.vanklink !

When this is merged, gap-deployment will need to get updated with new oss-params, could you handle this Aleks?

I can @karel.vanklink

merged