fix(index): Do not override the search analyzer for ngram fields

[iprentic]

Using the same analyzer for the index and search is already the default: https://www.elastic.co/guide/en/elasticsearch/reference/current/search-analyzer.html
By default, queries will use the analyzer defined in the field mapping

So, no need to specify it explicitly, and doing so causes the system update job to detect a difference between the field as exists in ES and the defined mapping when there isn't one.

Checklist

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