Disable autogenerating DatadogMetric for each HPA

[arapulido]

For the e2e tests, configure the Datadog Cluster Agent to not create autogenerated DatadogMetric objects for each HPA that is created.

This is the recommended way to deploy the Cluster Agent when using KEDA with the DCA, but this wasn't reflected in the tests configuration.

Checklist

• When introducing a new scaler, I agree with the scaling governance policy
• I have verified that my change is according to the deprecations & breaking changes policy
• Tests have been added
• Changelog has been updated and is aligned with our changelog requirements
• A PR is opened to update our Helm chart (repo) (if applicable, ie. when deployment manifests are modified)
• A PR is opened to update the documentation on (repo) (if applicable)
• Commits are signed with Developer Certificate of Origin (DCO - learn more)

Fixes #

Relates to #