Collapse Tracy threads by default.

Note that this will likely work only when loading existing traces. In live
captures the thread name may not have yet been retrieved at the point when
timeline item insertion occurs, which will prevent the check from succeeding.

server/TracyTimelineItemThread.cpp

@@ -16,6 +16,11 @@ TimelineItemThread::TimelineItemThread( View& view, Worker& worker, const Thread
     , m_thread( thread )
     , m_ghost( false )
 {
+    auto name = worker.GetThreadName( thread->id );
+    if( strncmp( name, "Tracy ", 6 ) == 0 )
+    {
+        m_showFull = false;
+    }
 }
 
 bool TimelineItemThread::IsEmpty() const