monitoring: make timeSeriesPanel default fillOpacity=8

Change default value of fillOpacity from 0 to 8 for
timeseries graphs.

Signed-off-by: Vallari Agrawal <[email protected]>

Author: VallariAg

monitoring/ceph-mixin/dashboards/utils.libsonnet

@@ -588,7 +588,7 @@ local timeSeries = import 'timeseries_panel.libsonnet';
     axisPlacement='auto',
     barAlignment=0,
     drawStyle='line',
-    fillOpacity=0,
+    fillOpacity=8,
     gradientMode='none',
     lineInterpolation='linear',
     lineWidth=0,