When we complete the current refactoring of the suggestion builders (#17096), we should add tests that check the output of the suggestion builders build() method, similar to what we did when refactoring the query builders. While we were refactoring the suggestion builders, we temporarily added tests that check that the results of parsing a builder in its xContent representation and calling the build() methods resulted in the same SuggestionSearchContext. After the deletion of SuggestParseElement we cannot use this kind of similarity check any more, so we need dedicated unit tests for that.