Fix: CmdRemoveRoadStop didn't validate the height property properly (#9945)

Height was a unsigned 32bit integer, where TileAddWrap uses a
signed 32bit integer for the height. In result, there was an
implicit cast from unsigned to signed, messing things up.

But looking at it from a functional perspective, allowing such
large values is not sensible. In fact, width is restricted to
just a 8bit integer. By changing height to a 8bit integer too,
the implicit cast will never make a positive value negative anymore.

src/station_cmd.cpp

@@ -2058,7 +2058,7 @@ static CommandCost RemoveRoadStop(TileIndex tile, DoCommandFlag flags)
  * @param remove_road Remove roads of drive-through stops?
  * @return The cost of this operation or an error.
  */
-CommandCost CmdRemoveRoadStop(DoCommandFlag flags, TileIndex tile, uint8 width, uint height, RoadStopType stop_type, bool remove_road)
+CommandCost CmdRemoveRoadStop(DoCommandFlag flags, TileIndex tile, uint8 width, uint8 height, RoadStopType stop_type, bool remove_road)
 {
 	if (stop_type >= ROADSTOP_END) return CMD_ERROR;
 	/* Check for incorrect width / height. */