use detailed service endpoint in notification summary page

to help get rid of notification statistics tables, move over the
job page. fortunately its required data format is almost identical
to the return value of the detailed service endpoint, so little
work is required - only to add a sending column

app/main/views/jobs.py

@@ -1,5 +1,4 @@
 # -*- coding: utf-8 -*-
-
 import time
 import dateutil
 from datetime import datetime, timedelta, timezone
@@ -21,7 +20,6 @@ from app import (
     job_api_client,
     notification_api_client,
     service_api_client,
-    statistics_api_client,
     current_service,
     format_datetime_short)
 from app.main import main
@@ -30,7 +28,7 @@ from app.utils import (
     generate_previous_next_dict,
     user_has_permissions,
     generate_notifications_csv)
-from app.statistics_utils import sum_of_statistics, statistics_by_state, add_rate_to_jobs
+from app.statistics_utils import add_rate_to_jobs
 from app.utils import get_help_argument
 
 
@@ -171,9 +169,6 @@ def view_notifications(service_id, message_type):
         template_type=[message_type],
         status=filter_args.get('status'),
         limit_days=current_app.config['ACTIVITY_STATS_LIMIT_DAYS'])
-    service_statistics_by_state = statistics_by_state(sum_of_statistics(
-        statistics_api_client.get_statistics_for_service(service_id, limit_days=7)['data']
-    ))
     view_dict = dict(
         message_type=message_type,
         status=request.args.get('status')
@@ -223,23 +218,11 @@ def view_notifications(service_id, message_type):
             message_type=message_type,
             status=request.args.get('status')
         ),
-        status_filters=[
-            [
-                item[0], item[1],
-                url_for(
-                    '.view_notifications',
-                    service_id=current_service['id'],
-                    message_type=message_type,
-                    status=item[1]
-                ),
-                service_statistics_by_state[message_type][item[0]]
-            ] for item in [
-                ['processed', 'sending,delivered,failed'],
-                ['sending', 'sending'],
-                ['delivered', 'delivered'],
-                ['failed', 'failed'],
-            ]
-        ]
+        status_filters=get_status_filters(
+            current_service,
+            message_type,
+            service_api_client.get_detailed_service(service_id)['data']['statistics']
+        )
     )
 
 
@@ -261,6 +244,34 @@ def view_notification(service_id, job_id, notification_id):
     )
 
 
+def get_status_filters(service, message_type, statistics):
+    stats = statistics[message_type]
+    stats['sending'] = stats['requested'] - stats['delivered'] - stats['failed']
+
+    filters = [
+        # key, label, option
+        ('requested', 'processed', 'sending,delivered,failed'),
+        ('sending', 'sending', 'sending'),
+        ('delivered', 'delivered', 'delivered'),
+        ('failed', 'failed', 'failed'),
+    ]
+    return [
+        # return list containing label, option, link, count
+        (
+            label,
+            option,
+            url_for(
+                '.view_notifications',
+                service_id=service['id'],
+                message_type=message_type,
+                status=option
+            ),
+            stats[key]
+        )
+        for key, label, option in filters
+    ]
+
+
 def _get_job_counts(job, help_argument):
     return [
         (