Always use explorer layout in datastores screen
Always use explorer layout in datastores screen

The process_show_list() would change the previously set @lastaction
to "show_list". We need to restore the explorer layout here, otherwise
the datastores screen would be incorrectly rendered with a listnav
controls on the left (rather than tree controls).

https://bugzilla.redhat.com/show_bug.cgi?id=1381614
(transferred from ManageIQ/manageiq@eba0427d7cef8aa02b08a3aede1f1d7f1943d1a6)

ManageIQ/manageiq-ui-classic,ManageIQ/manageiq-ui-classic,ManageIQ/manageiq-ui-classic,ManageIQ/manageiq-ui-classic