remove rest of letter callback

app/notifications/notifications_letter_callback.py

@@ -1,36 +0,0 @@
-import json
-from functools import wraps
-
-from flask import Blueprint, current_app, jsonify, request
-
-from app.config import QueueNames
-from app.notifications.utils import autoconfirm_subscription
-from app.schema_validation import validate
-from app.v2.errors import register_errors
-
-letter_callback_blueprint = Blueprint('notifications_letter_callback', __name__)
-register_errors(letter_callback_blueprint)
-
-
-dvla_sns_callback_schema = {
-    "$schema": "http://json-schema.org/draft-07/schema#",
-    "description": "sns callback received on s3 update",
-    "type": "object",
-    "title": "dvla internal sns callback",
-    "properties": {
-        "Type": {"enum": ["Notification", "SubscriptionConfirmation"]},
-        "MessageId": {"type": "string"},
-        "Message": {"type": ["string", "object"]}
-    },
-    "required": ["Type", "MessageId", "Message"]
-}
-
-
-def validate_schema(schema):
-    def decorator(f):
-        @wraps(f)
-        def wrapper(*args, **kw):
-            validate(request.get_json(force=True), schema)
-            return f(*args, **kw)
-        return wrapper
-    return decorator