Don't use PublicRoomsChunk::aliases

Doesn't seem to be part of the spec and currently isn't in libQuotient; if it comes back, we can revert this.
Until then, this fixes the build

src/publicroomlistmodel.cpp

@@ -157,10 +157,6 @@ QVariant PublicRoomListModel::data(const QModelIndex &index, int role) const
             return displayName;
         }
 
-        if (!room.aliases.isEmpty()) {
-            displayName = room.aliases.front();
-        }
-
         if (!displayName.isEmpty()) {
             return displayName;
         }