TOP-924: Trigger ska-low-csp-test pipeline

This updates the CI/CD pipeline configuration to automatically trigger the https://gitlab.com/ska-telescope/ska-low-csp-test pipeline after deploying the Helm chart. It works in two modes:

• On the main branch and on tags (releases), it simply deploys to the ska-low-csp-baseline namespace and then triggers the downstream pipeline to run the tests on it.
• On Merge Requests that update any of the Helm charts, it deploys to a dedicated namespace and then triggers the downstream pipeline to run the tests on that namespace instead of on the baseline. Since we can't have the baseline and this dedicated namespace running at the same time because of the hardware resources, it temporarily disables the baseline deployment, and restores it after the tests are finished.

I also updated the other jobs to only run when they are required, and removed all of the jobs that run any tests inside this repository.