[BUG] Rest APIs without feature flag enabled return incorrect error message

[dbwiddis]

What is the bug?

The Base REST handler tracks consumed parameters and content.

When a param is required, and is not consumed (via request.param("foo")) the Base Rest Handler overrides whatever message is returned to OpenSearch.

How can one reproduce the bug?

1. Start up OpenSearch but do not enable the Flow Framework feature flag.
2. Attempt to use any API that uses a named param for workflow ID (get, status, etc.)
3. Observe response:

{
    "error": {
        "root_cause": [
            {
                "type": "illegal_argument_exception",
                "reason": "request [/_plugins/_flow_framework/workflow/foobar] contains unrecognized parameter: [workflow_id]"
            }
        ],
        "type": "illegal_argument_exception",
        "reason": "request [/_plugins/_flow_framework/workflow/foobar] contains unrecognized parameter: [workflow_id]"
    },
    "status": 400
}

What is the expected behavior?

The specific error message produced by the API (for example, the need to enable the feature flag).

Do you have any additional context?

The fix is to consume the param prior to any attempted rest response, for example:

String workflowId = request.param("workflow_id");

This is a similar error to #274 but more critical to fix (thus BUG instead of FEATURE). Both this bug and #274 can/should be fixed at the same time.