[test] turn on host io cache for opensuse

The hope is that this will resolve the problems with very slow io we're
seeing on this box in elastic#30295

Vagrantfile

@@ -115,6 +115,11 @@ Vagrant.configure(2) do |config|
   'opensuse-42'.tap do |box|
     config.vm.define box, define_opts do |config|
       config.vm.box = 'elastic/opensuse-42-x86_64'
+
+      # https://github.com/elastic/elasticsearch/issues/30295
+      config.vm.provider 'virtualbox' do |vbox|
+        vbox.customize ['storagectl', :id, '--name', 'SATA Controller', '--hostiocache', 'on']
+      end
       suse_common config, box
     end
   end