Start date and end date values are sometimes misleading

[Conal-Tuohy]

The dates 1753-01-01 and 3000-12-31 are actually "sentinel" values that probably signify something like "before the start of records" and "until the present day". They should probably just be filtered out of the IIIF metadata array:

Label	Value
Start date	1753-01-01
End date	3000-12-31

See e.g. "D194 Picking coffee cherries" which appears on the catalogue page as "undated" but which in Solr has the 2 dates mentioned above in the start_dt and end_dt fields.

{
  "responseHeader":{
    "status":0,
    "QTime":0,
    "params":{
      "q":"(text:(\"D194 Picking coffee cherries\")) AND (iiif-manifest:(*))",
      "sort":"Series_title asc",
      "wt":"json"}},
  "response":{"numFound":1,"start":0,"docs":[
      {
        "category":"Item",
        "entity":"Record",
        "_id":"ADAAC82B-5613-11EB-BE8C-0FA8342FF25B",
        "timestamp":1622643392,
        "identifier.PROV_ACM.id":"VPRS 14517/P0001/4/176",
        "identifier.PID.id":"ADAAC82B-5613-11EB-BE8C-0FA8342FF25B",
        "title":"D194 Picking coffee cherries",
        "consignment_id":"P0001",
        "start_dt":"1753-01-01T00:00:00Z",
        "end_dt":"3000-12-31T00:00:00Z",
        "date_range":["[1753 TO 3000]"],
        "date_range.not_described":["[1753 TO 3000]"],
        "description.subject":["Coffee"],
        "description.aggregate":"Subject : Coffee",
        "presentation_text":"Subject : Coffee",
        "jurisdictional_coverage":["Victoria"],
        "rights_statement":["Open Public Records Act 1973"],
        "rights_status":["Open"],
        "item_discrete":"No",
        "format":"Physical",
        "medium":["Polyester Negative"],
        "location":["North Melbourne",
          "Online"],
        "access_restriction":"No",
        "status":"Published",
        "citation":"VPRS 14517/P0001/4, D194",
        "is_part_of_series.id":["VPRS14517"],
        "is_part_of_series.title":["Negatives of Photographs [Publications Branch]"],
        "series_id":"14517",
        "parents.ids":["VPRS14517",
          "D6BBC7A6-F7E6-11E9-AE98-0F840EB4F6E9"],
        "parents.titles":["Negatives of Photographs [Publications Branch]",
          "[Not Set]"],
        "agencies.titles":["Education Department"],
        "agencies.ids":["VA714"],
        "agencies.date_ranges":["[1873 TO 1985]"],
        "is_part_of_item.PID":["D6BBC7A6-F7E6-11E9-AE98-0F840EB4F6E9"],
        "is_part_of_item.title":["D1-D331"],
        "box_number":"12",
        "iiif-manifest":"https://images.prov.vic.gov.au/manifests/AD/AA/C8/2B/-5613-11EB-BE8C-0FA8342FF25B/images/manifest.json",
        "iiif-thumbnail":"https://images.prov.vic.gov.au/loris/AD%2FAA%2FC8%2F2B%2F-5613-11EB-BE8C-0FA8342FF25B%2Fimages%2F1%2Ffiles%2F14517-00012-D0194.tif/full/!200,200/0/default.jpg",
        "control_symbol_labels":["Registration Number"],
        "control_symbol_values":["D194"],
        "record_form":["Photograph or Image"],
        "_version_":1703891665329061888}]
  }
}