Unfail anomaly detection tests

[nikie]

Issue #, if available:
There are no user-facing changes.

Description of changes:

• Unfail anomaly detection tests by removing pytest.mark.xfail marks and asserting the failing statements with self.assertRaises, except for the test_anomalyDetector test which relates to a not implemented feature.
• Add assertions to the test_RelativeRateOfChangeStrategy test.
• Apply black formatting to anomaly detection tests.

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