More Like This Query Conditionless behaviour

[russcam]

Relates: https://stackoverflow.com/questions/55750953/more-like-this-query-not-getting-serialized-nest

More Like This Query is determined to be conditionless when Fields is conditionless, which is incorrect. The query should be conditionless only when Fields is conditionless and Like is conditionless.

[russcam]

Closing this as #3697 has been merged and will be in the next release.