Add files generated by `make test` to .gitignore (#4629)
Add files generated by `make test` to .gitignore (#4629)

Automatic merge from submit-queue.

Add files generated by `make test` to .gitignore
istio/istio,geeknoid/istio,istio/istio,frankbu/istio,smawson/istio,frankbu/istio,frankbu/istio,smawson/istio,smawson/istio,geeknoid/istio,istio/istio,frankbu/istio,geeknoid/istio,smawson/istio,geeknoid/istio,smawson/istio,geeknoid/istio,smawson/istio,frankbu/istio,istio/istio,geeknoid/istio,frankbu/istio,istio/istio