Description: bulk delete UI broken for custom fields
Steps to reproduce:
- Create a couple of custom fields
- Control Panel > Custom Fields > Document > Add new > Select Input Field
- Name: "test-field-1"
- Repeat for test-field-2
- Go back to Control Panel > Custom Fields > Document
- Select checkbox next to test-field-1
- ERROR #1 - Blue banner at the top says `1 of Selected` instead of `1 of 2 selected`
- Delete the selected custom field (top right trash icon)
- ERROR #2 - Success message appears, field is deleted, but the banner at the top remains
- Clicking on the trashcan again crashes the portlet: `*Error:*The custom field could not be found`
Expected: Blue banner says "1 of # selected"
Actual: Blue banner is missing the #
Expected: Blue banner disappears after action complete
Actual: Blue banner remains, and allows for portlet crash on trash re-click