Ability to turn off multiple requests for performance measurements

[conorsexton]

User story

As a developer testing microservices, I should be able to send mockups to my destination as one request per mockup, so that I’m not required to send redundant HTTP requests.

Acceptance criteria

• Destination panel has UI element to turn off performance metrics (or to turn off default behavior of sending HTTP request 10 times)
• Toggling the preference in the UI does prevent multiple HTTP requests
• Performance metrics for single request display as expected

Other possible approach

Since we send multiple mockups to the destination panel, we could calculate the average performance between them, instead of multiple requests per mockup.