Fix regular expression for vsphere datastores

The regular expression for vsphere datastores was not working as expected
when there were multiple datastores. This was because the regular expression
conflicted with using entombed credhub variables that are wrapped in
parenthesis, causing three parenthesis in a row.

overlay/cpis/vsphere.yml

@@ -11,9 +11,9 @@ meta:
   disk_path: (( concat genesis.env "/disks" ))
 
   joined_vsphere_ephemeral_datastores: (( join "|" params.vsphere_ephemeral_datastores ))
-  vsphere_ephemeral_datastores: (( concat "^(" meta.joined_vsphere_ephemeral_datastores ")$" ))
+  vsphere_ephemeral_datastores: (( concat "^(?:" meta.joined_vsphere_ephemeral_datastores ")$" ))
   joined_vsphere_persistent_datastores: (( join "|" params.vsphere_persistent_datastores ))
-  vsphere_persistent_datastores: (( concat "^(" meta.joined_vsphere_persistent_datastores ")$" ))
+  vsphere_persistent_datastores: (( concat "^(?:" meta.joined_vsphere_persistent_datastores ")$" ))
 
 bosh-variables:
   vcenter_dc: (( grab params.vsphere_datacenter ))