Remove provider_statistics_dao.get_provider_statistics

The provider_statistics table is no longer being populated, get rid of any reads from this table.

app/dao/provider_statistics_dao.py

@@ -1,9 +1,7 @@
-from sqlalchemy import func, cast, Float, case
+from sqlalchemy import func
 
 from app import db
 from app.models import (
-    ProviderStatistics,
-    ProviderDetails,
     NotificationHistory,
     SMS_TYPE,
     EMAIL_TYPE,
@@ -12,15 +10,6 @@ from app.models import (
 )
 
 
-def get_provider_statistics(service, **kwargs):
-    query = ProviderStatistics.query.filter_by(service=service)
-    if 'providers' in kwargs:
-        providers = ProviderDetails.query.filter(ProviderDetails.identifier.in_(kwargs['providers'])).all()
-        provider_ids = [provider.id for provider in providers]
-        query = query.filter(ProviderStatistics.provider_id.in_(provider_ids))
-    return query
-
-
 def get_fragment_count(service_id):
     shared_filters = [
         NotificationHistory.service_id == service_id,