Bug: GET /v1/pipelines should include associated processors

[raulb]

Bug description

Important

Fixing this issue would be nice since we could include the processors as part of conduit pipeline ls before we release 0.13.0

Working on #2019, I noticed that even though a pipeline contains a processor, the PipelineService doesn't include this information, appearing to be empty:

curl -X 'GET' \
  'http://localhost:8080/v1/pipelines' \
  -H 'accept: application/json'  
[
  {
    "id": "add-department",
    "state": {
      "status": "STATUS_RUNNING",
      "error": ""
    },
    "config": {
      "name": "add-department",
      "description": "An example pipeline which reads data (imaginary employees) from two generator sources, processes it and writes it to a file.\nIt attaches the built-in `field.set` processor to one of the sources to add a `department` field to its records. The records from the other source are not processed.\n"
    },
    "connectorIds": [
      "add-department:employees-1",
      "add-department:employees-2",
      "add-department:file-destination"
    ],
    "processorIds": [],
    "createdAt": "2025-01-09T12:23:13.737117Z",
    "updatedAt": "2025-01-09T12:23:13.737693Z"
  }
]

Here's my yaml

version: 2.2
pipelines:
  - id: add-department
    status: running
    description: >
      An example pipeline which reads data (imaginary employees) from two generator
      sources, processes it and writes it to a file.
      
      It attaches the built-in `field.set` processor to one of the sources
      to add a `department` field to its records. The records from the other source
      are not processed.
    connectors:
      - id: employees-1
        type: source
        plugin: builtin:generator
        settings:
          format.type: "structured"
          format.options.id: int
          format.options.name: string
          format.options.company: string
          format.options.trial: bool
          recordCount: "1"
        processors:
          - id: extract-name
            plugin: field.set
            settings:
              field: '.Payload.After.department'
              value: 'finance'
      - id: employees-2
        type: source
        plugin: builtin:generator
        settings:
          # department collection
          format.type: "structured"
          format.options.id: int
          format.options.name: string
          format.options.company: string
          format.options.trial: bool
          recordCount: "2"
      - id: file-destination
        type: destination
        plugin: builtin:file
        settings:
          path: ./example.out

Steps to reproduce

1. Make sure you have a pipeline with a processor.
2. Run conduit
3. Visit http://localhost:8080/openapi/#/PipelineService/PipelineService_ListPipelines and inspect the response on this request.
4. Notice processors are not included on the pipeline that has it.

Version

v0.13.0-nightly.20250110