Fix #9869: remove docking tile when doing a clear square

Terraforming through objects placed on water didn't properly remove docking tiles as expected.

By moving some logic regarding removal of docking tiles into DoClearSquare, the issue is solved, while also simplifying code, avoiding repetition elsewhere.

src/landscape.cpp

@@ -32,6 +32,7 @@
 #include "saveload/saveload.h"
 #include "framerate_type.h"
 #include "landscape_cmd.h"
+#include "station_func.h"
 #include <array>
 #include <list>
 #include <set>
@@ -574,8 +575,10 @@ void DoClearSquare(TileIndex tile)
 	/* If the tile can have animation and we clear it, delete it from the animated tile list. */
 	if (_tile_type_procs[GetTileType(tile)]->animate_tile_proc != nullptr) DeleteAnimatedTile(tile);
 
+	bool remove = IsDockingTile(tile);
 	MakeClear(tile, CLEAR_GRASS, _generating_world ? 3 : 0);
 	MarkTileDirtyByTile(tile);
+	if (remove) RemoveDockingTile(tile);
 }
 
 /**