[native] Do not show sidebars below matching top-level threads in the search results

Test Plan: Check if matching top-level threads are displayed without sidebars below when search text is not empty

Reviewers: ashoat, palys-swm

Reviewed By: ashoat

Subscribers: zrebcu411, Adrian, atul

Differential Revision: https://phabricator.ashoat.com/D571