fix: incorrect db query to fetch all saved searches if multiple orgs
Created by: attfarhan
Fixes https://github.com/sourcegraph/sourcegraph/issues/4058.
Fixes a bug where the saved searches page would not load at all if the user viewing it is part of more than one org. Also adds a test for this function.
This must be cherry-picked onto 3.4 cc @sourcegraph/distribution