fix: Disable monitoring addon when spec.Monitoring is false

[yiannistri]

What this PR does / why we need it:

The monitoring addon was not being disabled as per the spec.

Which issue(s) this PR fixes Issue #584

Special notes for your reviewer:

Checklist:

• [x] squashed commits into logical changes
• [ ] includes documentation
• [x] adds unit tests
• [ ] adds or updates e2e tests
• [x] backport needed