Schedule Gerrit's git garbage collection

We are seeing that Gerrit is spending a lot of time garbage collecting,
possibily because the JVM is starting the garbage collection too late
and thus trying to garbage collect too much.  This change schedules the
garbage collection daily which will allow Gerrit to garbage collect
in smaller chunks.  Hopefully this will help maintain Gerrit performance.

Garbage collection recommendations from Collabnet[1]:
"Running JGIT gc frequently is crucial for good fetch/push performance
as well as smooth source code browsing".

[1] http://tinyurl.com/q2aw6ba

Change-Id: If9f5d5879cffc5c6349166a70b4e00429b59576b
depends-on: I73166de7008ceb42db3db4a8b22fb6e9c94e790d

modules/openstack_project/manifests/gerrit.pp

@@ -30,6 +30,8 @@ class openstack_project::gerrit (
   $email = '',
   $database_poollimit = '',
   $container_heaplimit = '',
+  $gc_start_time = '',
+  $gc_interval = '',
   $core_packedgitopenfiles = '',
   $core_packedgitlimit = '',
   $core_packedgitwindowsize = '',
@@ -128,6 +130,8 @@ class openstack_project::gerrit (
     openidssourl                        => 'https://login.launchpad.net/+openid',
     database_poollimit                  => $database_poollimit,
     container_heaplimit                 => $container_heaplimit,
+    gc_start_time                       => $gc_start_time,
+    gc_interval                         => $gc_interval,
     core_packedgitopenfiles             => $core_packedgitopenfiles,
     core_packedgitlimit                 => $core_packedgitlimit,
     core_packedgitwindowsize            => $core_packedgitwindowsize,

modules/openstack_project/manifests/review.pp

@@ -108,6 +108,8 @@ class openstack_project::review (
       # 1 + 100 + 9 + 2 + 2 + 25 => 139(rounded up)
     database_poollimit                  => '150',
     container_heaplimit                 => '12g',
+    gc_start_time                       => '4:30',
+    gc_interval                         => '1 day',
     core_packedgitopenfiles             => '4096',
     core_packedgitlimit                 => '400m',
     core_packedgitwindowsize            => '16k',