chore(gae): fix region tags in standard_python3/pubsub/ (GoogleCloudPlatform#13133)

* chore(gae): add new region tags to app.yaml

* chore(gae): delete unused and add new region tags to main.py

Author: eapl-gemugami

appengine/standard_python3/pubsub/app.yaml

@@ -14,10 +14,12 @@
 
 runtime: python39
 
+# [START gae_standard_pubsub_env]
 #[START env]
 env_variables:
   PUBSUB_TOPIC: '<YOUR_TOPIC>'
   # This token is used to verify that requests originate from your
   # application. It can be any sufficiently random string.
   PUBSUB_VERIFICATION_TOKEN: '<YOUR_VERIFICATION_TOKEN>'
 #[END env]
+# [END gae_standard_pubsub_env]

appengine/standard_python3/pubsub/main.py

@@ -12,7 +12,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# [START app]
 import base64
 import json
 import logging
@@ -39,6 +38,7 @@
 CLAIMS = []
 
 
+# [START gae_standard_pubsub_index]
 # [START index]
 @app.route("/", methods=["GET", "POST"])
 def index():
@@ -58,9 +58,8 @@ def index():
     future = publisher.publish(topic_path, data)
     future.result()
     return "OK", 200
-
-
 # [END index]
+# [END gae_standard_pubsub_index]
 
 
 # [START gae_standard_pubsub_auth_push]
@@ -104,10 +103,9 @@ def receive_messages_handler():
     MESSAGES.append(payload)
     # Returning any 2xx status indicates successful receipt of the message.
     return "OK", 200
-
-
 # [END gae_standard_pubsub_auth_push]
 
+
 # [START gae_standard_pubsub_push]
 @app.route("/pubsub/push", methods=["POST"])
 def receive_pubsub_messages_handler():
@@ -118,9 +116,9 @@ def receive_pubsub_messages_handler():
     envelope = json.loads(request.data.decode("utf-8"))
     payload = base64.b64decode(envelope["message"]["data"])
     MESSAGES.append(payload)
+
     # Returning any 2xx status indicates successful receipt of the message.
     return "OK", 200
-
 # [END gae_standard_pubsub_push]
 
 
@@ -142,4 +140,3 @@ def server_error(e):
     # This is used when running locally. Gunicorn is used to run the
     # application on Google App Engine. See entrypoint in app.yaml.
     app.run(host="127.0.0.1", port=8080, debug=True)
-# [END app]