Search: Fix race condition with results display

Since results are now run through an asynctask before they are added
this created a race condition which lead to the screen sometimes
showing 'no results found' when results are actually available

Ticket: QRDL-995
Change-Id: I5b7ddb44c16603fac7ceca3f955038cc3d646de8
(cherry picked from commit 1a23b92d)