Don't hide HTTP error in orka client

What does this MR do?

Raises an exception when a request to Orka from the Python side fails

Why was this MR needed?

This job was successful but there was a hidden error https://gitlab.com/gitlab-org/ci-cd/shared-runners/images/macstadium/orka/-/jobs/1594136422

What's the best way to test this MR?

Un-protect the GITLAB_TOKEN variable. Run a pipeline with FORCE_CLEANUP and CI_MERGE_REQUEST_IID set. Example with exception being raised: https://gitlab.com/gitlab-org/ci-cd/shared-runners/images/macstadium/orka/-/jobs/1595789603

What are the relevant issue numbers?