Room list: hide the empty/collapse icon when the room list is empty (#33814)

* fix: don't display the empty/collapse icon when the room list is empty

* Fix jest lcov projectRoot config

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Co-authored-by: Michael Telatynski <7t3chguy@gmail.com>

apps/web/src/viewmodels/room-list/RoomListViewModel.ts

@@ -699,7 +699,7 @@ function computeSections(
             ...section,
             rooms: isSectionExpanded(section.tag) ? section.rooms : [],
         }));
-    const isFlatList = sections.length === 1 && sections[0].tag === CHATS_TAG;
+    const isFlatList = sections.length === 0 || (sections.length === 1 && sections[0].tag === CHATS_TAG);
 
     return { sections, isFlatList };
 }