prefix druid with "druid:" for data going into 979 subfield b

[shelleydoljack]

On a dag run for add 979, I see that the subfield b is not prefixed with "druid:". I'm not entirely sure if this will break SW indexing, see https://github.com/sul-dlss/searchworks_traject_indexer/blob/15a87c4d311db4bd4aad12343c884d62ded61a00/lib/traject/config/folio_config.rb#L2226 or have some other deleterious effect (like doesn't facet right or something).

The return_value in the XCOM for add_979_marc_tags was:

{'979': [{'ind1': ' ', 'ind2': ' ', 'subfields': [{'f': ''}, {'b': 'bt942vy4674'}, {'c': 'bt942vy4674_00_0001.jp2'}, {'d': 'Stanford Law Library in Memory of Henry Vrooman'}]}]}

See dag run.

This is the config I used to trigger the dag run:

{
  "druids_for_instance_id": {
    "ab09f8e4-6967-4d72-9c70-2ab70da85c4e": [
      {
        "druid": "bt942vy4674",
        "fund_name": "",
        "image_filename": "bt942vy4674_00_0001.jp2",
        "title": "Stanford Law Library in Memory of Henry Vrooman"
      }
    ]
  }
}