[QA] enable SEND_SCENARIO_LINE_REFERENCES by default and do not pass xRequestId param

[saw-jan]

env SEND_SCENARIO_LINE_REFERENCES is used to enable and disable the generation of scenario line as the HTTP request id. We should make this true by default and even maybe remove the env.

Almost all the methods accept xRequestId param but having it as a method param can lead it to be empty if we forget to pass it. So, the better implementation would be to store the current scenario ref and use it in the guzzle request object directly. And then we can remove the param from all methods. This also makes sure that every request has a defined request id.

TODO:

• remove SEND_SCENARIO_LINE_REFERENCES and enable it by default
• use saved xRequestId directly in the guzzle request object.