sample-app: Use hardcoded URL as db-insert trigger subscriber

This is needed because the node-server service listens on port 8080, and
the K8s ref resolver doesn't support custom ports [1], and referring to
the node-server-svc service yields:

  http://node-server-svc.default.svc.cluster.local/insert

Instead of the correct URL:

  http://node-server-svc.default.svc.cluster.local:8080/insert

Which results in hanging connections and eventually timeouts when adding
new comments that pass the trigger's filter.

[1] https://github.com/knative/pkg/blob/dcf159339de2fec9dde678a04cb7a354e912d2bf/resolver/addressable_resolver.go#L227

Signed-off-by: Guzman <guzman@guzman.fi>

code-samples/eventing/bookstore-sample-app/solution/node-server/config/200-broker.yaml

@@ -15,8 +15,4 @@ spec:
       type: moderated-comment # This is the filter that will be applied to the event, only events with the ce-type moderated-comment will be processed
       badwordfilter: good # This is the filter that will be applied to the event, only events with the ce-extension badwordfilter: good will be processed
   subscriber:
-    ref:
-      apiVersion: v1
-      kind: Service
-      name: node-server-svc
-    uri: /insert # This is the path where the event will be sent to the subscriber, see /insert in node-server code: index.js
+    uri: http://node-server-svc.default.svc.cluster.local:8080/insert # This is the path where the event will be sent to the subscriber, see /insert in node-server code: index.js

docs/bookstore/page-6/advanced-event-filtering.md

@@ -36,11 +36,7 @@ Append the following Trigger configuration to the existing `node-server/config/2
           type: moderated-comment # This is the filter that will be applied to the event, only events with the ce-type moderated-comment will be processed
           badwordfilter: good # This is the filter that will be applied to the event, only events with the ce-extension badwordfilter: good will be processed
       subscriber:
-        ref:
-          apiVersion: v1
-          kind: Service
-          name: node-server-svc
-        uri: /insert # This is the path where the event will be sent to the subscriber, see /insert in node-server code: index.js
+        uri: http://node-server-svc.default.svc.cluster.local:8080/insert # This is the path where the event will be sent to the subscriber, see /insert in node-server code: index.js
     ```
 
 ```shell