(common) explicitly set leapsecmode to 'system'

This is the default behavior and setting the kernel the TAI offset does
not work with any other leapsecmode.

hieradata/common.yaml

@@ -68,6 +68,7 @@ lookup_options:
 
 hosts::purge_hosts: true
 timezone::timezone: "UTC"
+chrony::leapsecmode: "system"
 chrony::leapsectz: "right/UTC"
 ssh::storeconfigs_enabled: false
 ssh::server_options:

spec/spec_helper.rb

@@ -198,6 +198,13 @@ def node_files
       },
     )
   end
+
+  it do
+    is_expected.to contain_class('chrony').with(
+      leapsecmode: 'system',
+      leapsectz: 'right/UTC',
+    )
+  end
 end
 
 shared_examples 'lhn sysctls', :lhn_node do