Allow term autocomplete queries on twm_suggest

The content of twm_suggest should never be returned as part of the search result. But for autcomplete implementations that use the Terms Component (like the default in Search API Autocomplete named "Retrieve from server") the user might select a suggester field.
No mater if he selected it erroneously or on purpose, allowing the Terms Component is something different that returning the entire content and should be possible (as feature).