Description of problem:
It should be easier to delete content hosts where registration failed (e.g. when registering in scale). Issue which caused registration to fail is not subject of this bugzilla.


Version-Release number of selected component (if applicable):
satellite-6.2.0-8.2.beta.el7sat.noarch


How reproducible:
always


Steps to Reproduce:
1. Have few content hosts, where registration failed, e.g. with some of
   the error messages bellow:
     Task <uuid>: RestClient::InternalServerError: 500 Internal Server Error
     There was an issue with the backend service pulp: Pulp message bus connection issue.
     There was an issue with the backend service pulp: 500 Internal Server Error
2. Attempt to delete these content hosts:
   Hosts -> Content Hosts -> tick few of them -> Bulk Actions -> Remove Hosts


Actual results:
Now deleting task fails because some of its sub-tasks fails. To make it pass, you have to:

1. Go to failed parent task's sub tasks
2. Find these with State: stopped/Result: error
3. Open the link in the Error message which says:

> Required lock is already taken by other running tasks.
> Please inspect their state, fix their errors and resume them.
>
> Required lock: read
> Conflicts with tasks:
> - https://<fqdn>/foreman_tasks/tasks/b1654849-ec92-4e9e-bd68-78d925a2a8d4

4. Click [Dynflow Console] (make sure this works - because page is autoreloading, sometimes you have to click multiple times to make it work)
5. Click "Skip" at red row
6. Click resume and see the task to change from paused / warning to stopped / warning
7. Go back to Hosts -> Content Hosts
8. Select system(s) which had the problem again and delete it using bulk actions


Expected results:
There should be some workflow where this all would be possible via simmilar number of clicks as single ... -> Bulk Actions -> Remove Hosts


Additional info:
Imagine use case as I was solving: I was registering via subscription-manager in bunches 10 of 100 clients in parallel (1000 clients in total) and in different of these bunches few hosts failed. I have ended with 23 invalid profiles. When I have attempted to delete these, it meant 115+ clicks on Satellite webUI. There seems not to be a way to script this via Hammer (looks like there is simply no required API).