loki: increase split_queries_by_interval to 24h

The cloud server running Loki isn't powerful enough to do aggressive
query splitting; it makes queries execute slower and generates a lot
more queries, resulting in "too many outstanding requests" in recent
Loki versions. (Maybe a bug?)

roles/loki/files/loki.yaml

@@ -49,6 +49,7 @@ limits_config:
   max_query_series: 10000
   retention_period: 31d
   max_query_lookback: 31d
+  split_queries_by_interval: 24h
 
 analytics:
   reporting_enabled: false