Reduce Loki maxLines from 5000 to 500 to fix browser freezing

React performance violations in browser console show JavaScript
blocking the main thread while processing log data:
- 'message' handler took 206ms
- Forced reflow took 33ms
- 'focusout' handler took 150ms

Root cause: Grafana trying to render too many log lines at once
causes React components to block the browser UI thread.

Solution: Limit to 500 lines (down from 5000) to reduce data
processing and rendering load in the browser.

Author: jsprague84

grafana-datasources.yml

@@ -9,9 +9,10 @@ datasources:
     editable: true
     timeout: 30
     jsonData:
-      maxLines: 5000
+      maxLines: 500
       timeout: 30
       # Query performance settings
       derivedFields: []
+      # Disable live queries to reduce browser load
       # Default time range (helps prevent huge queries)
       # Users can still change this in the UI