Fix loglevel set up for Openstack services

Invalid Jinja2 statement used in
oslo_templates/files/logging/_logging.conf
It returns empty value for 'app_name' Jinja2 variable
substiution, so default level 'INFO'
has been always applied for logger_<app_name>, which
prevented from actual loglevel changing for Openstack daemons
which use oslo lib for logging.

Change-Id: Ia1ed5266e550cbd334d88c8c2d07f232bcb3ea89
Closes-Bug: PROD-26269
diff --git a/oslo_templates/files/logging/_logging.conf b/oslo_templates/files/logging/_logging.conf
index 20fa734..580fc89 100644
--- a/oslo_templates/files/logging/_logging.conf
+++ b/oslo_templates/files/logging/_logging.conf
@@ -20,7 +20,7 @@
 handlers = {{ log_handlers | join(", ") }}
 
 [logger_{{ app_name }}]
-level = {{ _data.get('loggers', {}).get('{{ app_name }}', {}).get('level', 'INFO') }}
+level = {{ _data.get('loggers', {}).get(app_name, {}).get('level', 'INFO') }}
 handlers = {{ log_handlers | join(", ") }}
 qualname = {{ app_name }}
 propagate = 0