Purge unmanaged files from nrpe.d

Signed-off-by: Nick Chappell <nick@intronic.org>

Merged from: https://github.com/Icinga/puppet-icinga2/pull/39

refs#7673: https://dev.icinga.org/issues/7673

manifests/nrpe/config.pp

@@ -24,6 +24,8 @@ class icinga2::nrpe::config inherits icinga2::nrpe {
     owner   => 'root',
     group   => 'root',
     mode    => '0755',
+    purge   => true,
+    recurse => true,
     require => Package[$icinga2::params::icinga2_client_packages],
   }