Optimize code size for tiled-layer.ts

[dumganhar]

Re: #

Changelog

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Continuous Integration

This pull request:

• needs automatic test cases check.

  Manual trigger with @cocos-robot run test cases afterward.

• does not change any runtime related code or build configuration

  If any reviewer thinks the CI checks are needed, please uncheck this option, then close and reopen the issue.

---

Compatibility Check

This pull request:

• changes public API, and have ensured backward compatibility with deprecated features.
• affects platform compatibility, e.g. system version, browser version, platform sdk version, platform toolchain, language version, hardware compatibility etc.
• affects file structure of the build package or build configuration which requires user project upgrade.
• introduces breaking changes, please list all changes, affected features and the scope of violation.

[github-actions]

Code Size Check Report

Wechat (WASM)	Before	After	Diff
2D Empty (legacy pipeline)	1005779 bytes	1005779 bytes	✅ 0 bytes
2D All (legacy pipeline)	2669492 bytes	2668281 bytes	👍 -1211 bytes
2D All (new pipeline)	2757999 bytes	2756788 bytes	👍 -1211 bytes
(2D + 3D) All	10013883 bytes	10012667 bytes	👍 -1216 bytes

Web (WASM + ASMJS)	Before	After	Diff
(2D + 3D) All	16829448 bytes	16828232 bytes	👍 -1216 bytes

Interface Check Report

! WARNING this pull request has changed these public interfaces:

@@ -55099,11 +55099,11 @@
         protected _diffX1?: number;
         protected _diffY1?: number;
         protected _useAutomaticVertexZ?: boolean;
         protected _vertexZvalue?: number;
-        protected _offset?: math.Vec2;
+        protected _offset: math.Vec2;
         protected _tiledDataArray: __private._cocos_tiledmap_tiled_layer__TiledDataArray;
-        protected _cameraNode?: Node;
+        protected _cameraNode: Node | null;
         get tiledDataArray(): __private._cocos_tiledmap_tiled_layer__TiledDataArray;
         get leftDownToCenterX(): number;
         get leftDownToCenterY(): number;
         constructor();
@@ -55433,9 +55433,8 @@
          */
         _tiledDataArrayIdx: number;
         protected _render(ui: __private._cocos_2d_renderer_i_batcher__IBatcher): void;
         protected createRenderEntity(): __private._cocos_2d_renderer_render_entity__RenderEntity;
-        prepareDrawData(): void;
     }
     /**
      * @en Renders the TMX object group.
      * @zh 渲染 tmx object group。