Creating indexes in `ch12/0.ch12.setup.ipynb` generates Solr errors

[alexott]

Delete dynamic field
Status: Failure; Response:[ {'responseHeader': {'status': 400, 'QTime': 89}, 'error': {'metadata': ['error-class', 'org.apache.solr.api.ApiBag$ExceptionWithErrObject', 'root-error-class', 'org.apache.solr.api.ApiBag$ExceptionWithErrObject'], 'details': [{'delete-dynamic-field': {'name': '*_ngram'}, 'errorMessages': ["The dynamic field '*_ngram' is not present in this schema, and so cannot be deleted.\n"]}], 'msg': 'error processing commands', 'code': 400}} ]

[treygrainger]

@dcrouch26 Can you look at this one when refactoring. There's duplication in a lot of the setup notebooks (setting up the same datasets in different places with only slight variations) in chapters 11-15 that should be cleaned up, and this is probably in some of that code.

[alexott]

Tracked in #120