[BUG] Have project-get-set-iteration-field.yaml not fail after linked issue is updated

[mroeschke]

I believe if a PR links an invalid/incorrectly formatted(?) issue, this workflow will fail with

gh: The iteration Id does not belong to the field
{"data":{"updateProjectV2ItemFieldValue":null},"errors":[{"type":"VALIDATION","path":["updateProjectV2ItemFieldValue"],"locations":[{"line":3,"column":9}],"message":"The iteration Id does not belong to the field"}]}

and even if the linked issue is corrected, this job will continue to fail

e.g.

https://github.com/rapidsai/cudf/actions/runs/13145770622/job/36683471245?pr=17760
https://github.com/rapidsai/cudf/actions/runs/13207892718/job/36875291888?pr=17954

[mroeschke]

In particular it is because in the .github/workflows/project-get-set-iteration-field.yaml workflow steps.get_iteration_option_id.outputs.ITERATION_OPTION_ID can be set to null e.g.

  # Set the iteration based on the query above
  # This overwrites whatever was in it before, we may want to make an "OVERWRITE" option
  gh api graphql -f query='
    mutation {
      updateProjectV2ItemFieldValue(
        input: {
          projectId: "..."
          itemId: "..."
          fieldId: "..."
        value: {
          iterationId: "null"
          }
        }
      ) {
          projectV2Item {
          id
          }
      }
      }'
  shell: /usr/bin/bash -e {0}
  env:
    GH_TOKEN: ***
gh: The iteration Id does not belong to the field