Description of problem:
The following error shows when canceling retirement of an orchestration stack:

ActionController::RoutingError (No route matches [GET] "/manageiq/providers/cloud_manager/orchestration_stack/show_list"):
...

Version-Release number of selected component (if applicable):
CFME 5.6

How reproducible:
Always

Steps to Reproduce:
1. Compute -> Clouds -> Stacks
2. Check a stack from the list
3. Policy -> Set retirement date
4. Cancel the form (i.e. do not submit)

Actual results:
The error above.


Expected results:
No error.

Additional info:
https://github.com/ManageIQ/manageiq/pull/10059