Use specific istio version in the kiali downstream pipeline

Currently, the Kiali jobs ( integration, cypress ) run the Kiali hack scripts for setting up demo projects. Those scripts download the latest Istio version.
To align with the SMCP version, the specific Istio version should be used.
Also, with each run, the scripts request to GitHub API which can cause an error in the pipeline due to `GitHub API Rate Limit Exceeded`. (especially during busy days)