Change runtimes to accept string

Currently the runtime is a drop down menu with only
"runc" option. User is not able to enter new runtimes
configured by them. So this patch changes the field to
accept any user input string for runtime.

Change-Id: I5e60dd782b799c013a492f823f144cfbe5fdfc15

zun_ui/static/dashboard/container/containers/actions/workflow/workflow.service.js

@@ -52,10 +52,6 @@
         {value: "always", name: gettext("Always")},
         {value: "unless-stopped", name: gettext("Unless Stopped")}
       ];
-      var runtimes = [
-        {value: "", name: gettext("Select runtime.")},
-        {value: "runc", name: gettext("runc")}
-      ];
 
       // schema
       schema = {
@@ -285,9 +281,8 @@
                   items: [
                     {
                       key: "runtime",
-                      type: "select",
+                      placeholder: gettext("The runtime to create container with."),
                       readonly: action === "update",
-                      titleMap: runtimes
                     }
                   ]
                 }