Slow responses in try now don't clear response area

[colvinco]

When using try more than once for an operation, the old response remains present until the new response is processed. In the absence of other feedback it can be misleading because it's not obvious that a new request is still in progress. If you aren't paying close attention it's easy to be confused by it.

Looking at it closely, the font changes slightly but that's all. It would be better to clear the response area every time Try is pressed, or do something else to indicate that the request is in process.

Repro in Chrome

1. Go to https://rapidocweb.com/examples/example1.html#get-/pet/-petId-
2. Set petId and press Try
3. Open Browser Dev Tools (F12) Network Tab, and enabling throttling
4. Change the petId and press Try again
5. The old response's font changes slightly but otherwise remains present until the new response arrives