Cluster Auditor helm test: resolve failures/add retries

See this example failure: https://repo1.dso.mil/platform-one/big-bang/bigbang/-/pipelines/973547 - the dashboard has no data in it when Cypress checks.

This appears to be a timing issue with the test. To resolve this we can make a couple of changes:

• Modify the prometheus test to check the specific target and validate it is up: See the example in kyverno reporter
• Modify the grafana test to add retries: See the example in Kyverno reporter

We may also want to remove this test since it just checks the existence of the dashboard and overlaps with the main grafana test.