Block build requests until environment builder is ready (#437)

* Add readiness probe
* Remove builder manager http api interface since we don’t use/need it
* Check environment builder status and block build requests until builder is ready
* Replace deprecated api extension interface
* Add healthy check to python env

test/test_utils.sh

@@ -207,6 +207,9 @@ wait_for_services() {
 
     wait_for_service $id controller
     wait_for_service $id router
+
+    echo Waiting for service is routable...
+    sleep 10
 }
 
 helm_uninstall_fission() {(set +e