Disable systemd service file creation (crowbar#19)

Enforce skip_enable option for monasca_setup

'skip_enable' option controls the creation of systemd service file for
Monasca Agent. The service file is created in RPM package, so the option
has to be enabled here.

chef/cookbooks/monasca/templates/default/monasca-reconfigure.erb

@@ -28,4 +28,5 @@
     --max_measurement_buffer_size '<%= @agent_settings["max_measurement_buffer_size"].to_i %>' \
     --backlog_send_rate '<%= @agent_settings["backlog_send_rate"].to_i %>' \
     --amplifier '<%= @agent_settings["amplifier"] %>' \
+    --skip_enable \
     <% if @install_plugins_only -%> --install_plugins_only <% end -%>