Fix series override alias for G1 old gen gc metric

Change-Id: Ice4908d335214749989966219fad410c783652af

dashboards/gerrit/process/panels/gc-time.libsonnet

diff --git a/dashboards/gerrit/process/panels/gc-time.libsonnet b/dashboards/gerrit/process/panels/gc-time.libsonnet
index 395b6dc..94e46b8 100644
--- a/dashboards/gerrit/process/panels/gc-time.libsonnet
+++ b/dashboards/gerrit/process/panels/gc-time.libsonnet
@@ -55,7 +55,7 @@
 )
 .addSeriesOverride(
   {
-    alias: 'gc time G1 young gen',
+    alias: 'gc time G1 old gen',
     color: '#F2CC0C',
   }
 )