search: restructure zoektGlobalQuery to only include q once

Created by: keegancsmith

Previously from a query "q" created a query that looked like this:

(OR (AND q public...) (AND q private...))

Now we create the query:

(AND q (OR public... private...))

I believe it is much faster for zoekt to evaluate. If I am not mistaken this will half the matchtree size.

Co-authored-by: @eseliger