Fix pipeline cancel command to cascade to child pipelines

What does this MR do and why?

Issue: #273378 (closed)

MR this builds on: !82347 (merged)

Another draft approach was started here: !82149 (diffs)

This MR fixes pipeline cancelations only causing parent pipelines to cancel.

All child pipeline jobs and parent pipeline jobs cancel when a given pipeline is cancelled.

This approach takes on tech debt because it handles the logic about getting the child pipelines in 2 places(CancelPendingPipelines and in cancel_running) by passing in a cascade_to_decendants parameter, because queries were optimized for timeouts in CancelPendingPipelines and in the interest of fewer changes at once. #355047

Screenshots or screen recordings

How to set up and validate locally

1. Setup a .gitlab-ci.yml that looks like:

     microservice_a:
       trigger:
         include: path/to/microservice_a.yml
   
     microservice_b:
       trigger:
         include: path/to/microservice_a.yml
   
     job1:
       script: sleep 10
   
     job2:
       script: sleep 10

2. Add a second file in the same project path/to/microservice_a.yml

   nested_servicea:
       trigger: 
           include: nested_service.yml
   
   nested_serviceb:
       trigger: 
           include: nested_service.yml
   
   job1:
       script: sleep 30
   

3. Setup another CI file nested_service.yml

   job1:
       script: sleep 30

4. Run the pipeline a few times cancelling at various times. Through the ui or api (Illustrated below):

# Using httpie
http POST "http://localhost:3000/api/v4/projects/<project_id>/pipeline?ref=main" "PRIVATE-TOKEN: <api_token>"
http POST "http://localhost:3000/api/v4/projects/<project_id/pipelines/<pipeline_id>/cancel" "PRIVATE-TOKEN: <api_token>"

1. Observe that the jobs/pipelines in the children(including nested children) both have the status of canceled

rails c
[97] pry(main)> Ci::Pipeline.find(pipeline_id).builds_in_self_and_descendants.map {|x| [x.status, x.id, x.pipeline.id, x.pipeline.root_ancestor.id, x.class.name] }

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.

Related to #273378 (closed)