[Test Framework] Fix outbound check for Echo (#14166)
[Test Framework] Fix outbound check for Echo (#14166)

It's not entirely clear why this change was needed,
but it seems to be working.

Another interesting thing is that [this unit test](https://github.com/istio/istio/blob/master/pkg/test/framework/components/echo/common/envoy_test.go) was still passing with the old code. Nothing immediately stood out as a difference between the old and new config dumps.

Fixes #14084
istio/istio,smawson/istio,smawson/istio,smawson/istio,smawson/istio,smawson/istio,geeknoid/istio,istio/istio,istio/istio,geeknoid/istio,geeknoid/istio,geeknoid/istio,smawson/istio,istio/istio,istio/istio,geeknoid/istio,geeknoid/istio