Remove DFS_QUERY_AND_FETCH as a search type

[Mpdreamz]

elastic/elasticsearch#22787

[gmarz]

Pending my comment on elastic/elasticsearch#22787

[s1monw]

you can't use this search type since 2.0 via rest. I think you can just trash it

[gmarz]

@s1monw thanks, we got this confused with dfs_query_THEN_fetch. We've already removed it in our 5.x branch.