Revert Websocket in Duo WF service work

Problem

As part of &17442 (closed) code changes were introduced to the Duo Workflow service to allow for websocket connections.

Those are no longer necessary since we opted to go with a different architecture instead.

Desired Outcome

Code changes introduced in gitlab-org/duo-workflow/duo-workflow-service!433 (merged) gitlab-org/modelops/applied-ml/code-suggestions/ai-assist!2614 (merged) gitlab-org/modelops/applied-ml/code-suggestions/ai-assist!2508 (merged) need to be reverted.