SUSE-flavored systems uses STARTMODE and not ONBOOT

As described in /etc/sysconfig/network/ifcfg.template

Static template was already using the right one, but the dhcp configuration seems
to be copied from a Fedora/Redhat template.
This fixes the issue that the interface does not come up after reboot.

templates/guests/suse/network_dhcp.erb

@@ -1,6 +1,6 @@
 #VAGRANT-BEGIN
 # The contents below are automatically generated by Vagrant. Do not modify.
-BOOTPROTO=dhcp
-ONBOOT=yes
-DEVICE=eth<%= options[:interface] %>
+BOOTPROTO='dhcp'
+STARTMODE='auto'
+DEVICE='eth<%= options[:interface] %>'
 #VAGRANT-END

test/unit/templates/guests/suse/network_dhcp_test.rb

@@ -12,9 +12,9 @@ describe "templates/guests/suse/network_dhcp" do
     expect(result).to eq <<-EOH.gsub(/^ {6}/, "")
       #VAGRANT-BEGIN
       # The contents below are automatically generated by Vagrant. Do not modify.
-      BOOTPROTO=dhcp
-      ONBOOT=yes
-      DEVICE=ethen0
+      BOOTPROTO='dhcp'
+      STARTMODE='auto'
+      DEVICE='ethen0'
       #VAGRANT-END
     EOH
   end