[FTS] queries should work when using the ngram and edge_ngram analyzers

This relates to MB-20467, during which it was discovered that doing match_phrase search on a field which had an analyzer that included the edge_ngram (back edge) did not work correctly.

Unfortunately, MB-20467 has also uncovered additional problems which should be resolved eventually. But, the more pressing issue is that we ensure that users who want to use ngrams, can do so without any complications.

This issue is thus broken out to focus on correcting this case.