Reduce retention of stats.timers

These stats.timers make up the bulk of our graphite data and are filling
the disk of the server. Reduce retention for them specifically to cut
back on disk demands.

Change-Id: Iba85c361fd70a8511c6fbb9da5123c650b11dec1

manifests/init.pp

@@ -10,6 +10,11 @@ class graphite(
       'pattern'    => '^carbon\.',
       'retentions' => '60:90d',
     },
+    {
+      'name'       => 'stats.timers',
+      'pattern'    => '^stats.timers.*',
+      'retentions' => '10s:8h,60s:7d,1h:90d,1d:1y',
+    },
     {
       'name'       => 'stats',
       'pattern'    => '^stats.*',