Programmatically launching backfills in a single run

[nsteins]

Hi, I have several assets that are configured with BackfillPolicy.single_run, which works properly when backfills are launched using the UI. I would like the ability to launch backfills from inside a python script that respects this single run policy. I have attempted to do this using the GraphQL API, but it launches separate runs for each partition:

mutation positionsBackfill(
      $partitionSetName: String!
    )
    {
      launchPartitionBackfill(backfillParams: {
        selector: {
          partitionSetName: $partitionSetName
          repositorySelector: {
            repositoryName: "__repository__"
            repositoryLocationName: "repo_name"
          }
        }
        partitionNames: ["2024-09-01","2024-09-02","2024-09-03","2024-09-04"]
        forceSynchronousSubmission: true
      }) 
      {
        ... on LaunchBackfillSuccess {
          backfillId
          launchedRunIds
        }
        ... on PipelineConfigValidationInvalid {
          pipelineName
          errors {
            message
            reason
          }
        }
        ... on Error {
            message
        }
      }
    }

[garethbrickman]

I believe this is blocked by: #5428