RFE: Add locust test in Keptn sequence before running evaluation in datadog-service tests

[vadasambar]

Problem statement.
We don't use locust tests before running datadog-service tests (test shipyard here). Because we have no locust tests, we are not able to test the deploy -> test -> evaluate sequence (example)

Describe the solution you'd like
I would like the go tests to use locust tests. Integration tests Github workflow should pass.

Describe alternatives you've considered
I haven't considered any other alternative.

Definition of Done

1. go tests use locust test files
2. shipyard has a test sequence
3. go tests pass with locust test and test sequence in shipyard
4. integration tests github workflow passes successfully (runs once every weekday)