Make indentation of generated log config consistent

(we had a mix of 2- and 4-space indents)

synapse/config/logger.py

@@ -29,8 +29,8 @@ version: 1
 
 formatters:
     precise:
-   format: '%(asctime)s - %(name)s - %(lineno)d - %(levelname)s - %(request)s\
+        format: '%(asctime)s - %(name)s - %(lineno)d - %(levelname)s - \
-- %(message)s'
+%(request)s - %(message)s'
 
 filters:
     context: