Add tests for global configuration attributes

[swiatekm]

The Chart allows various attributes to be set for all eligible resources. A simple example are labels, where we always set some common labels on all resources.

These properties should be covered by tests. A test for common labels is already present, but there are other properties which should be tested this way:

• sumologic.pullSecrets
• sumologic.podLabels
• sumologic.podAnnotations
• sumologic.serviceAccount.annotations

and possibly more.

This issue tracks adding these tests.