add contour tls testing in github actions

Author: dprotaso

.github/workflows/kind-e2e.yaml

@@ -94,6 +94,7 @@ jobs:
         # Disabled due to flakiness: https://github.com/knative/serving/issues/14637
         # - istio-ambient
         - contour
+        - contour-tls
         - gateway_istio
         - gateway_contour
 
@@ -135,6 +136,10 @@ jobs:
           ingress-class: kourier
           enable-tls: 1
 
+        - ingress: contour-tls
+          ingress-class: contour
+          enable-tls: 1
+
         - test-suite: runtime
           test-path: ./test/conformance/runtime/...