Optimize LabelComponent

[yanjifa]

Re: #

Changelog

• en: cc.Label._actualFontSize does not need to be serialized, as it will be calculated in real-time during actual rendering.
• zh: cc.Label._actualFontSize 没有必要序列化，实际渲染时会实时计算

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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.

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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.

[yanjifa]

@star-e Please assign a reviewer

[github-actions]

Code Size Check Report

Wechat (WASM)	Before	After	Diff
2D Empty (legacy pipeline)	1006343 bytes	1006252 bytes	👍 -91 bytes
2D All (legacy pipeline)	2671535 bytes	2671440 bytes	👍 -95 bytes
2D All (new pipeline)	2760985 bytes	2760891 bytes	👍 -94 bytes
(2D + 3D) All	10017290 bytes	10017194 bytes	👍 -96 bytes

Web (WASM + ASMJS)	Before	After	Diff
(2D + 3D) All	16838813 bytes	16838717 bytes	👍 -96 bytes

Interface Check Report

! WARNING this pull request has changed these public interfaces:

@@ -2407,12 +2407,12 @@
         get verticalAlign(): VerticalTextAlignment;
         set verticalAlign(value: VerticalTextAlignment);
         /**
          * @en
-         * The actual rendering font size in shrink mode.
+         * The actual rendering font size.
          *
          * @zh
-         * SHRINK 模式下面文本实际渲染的字体大小。
+         * 文本实际渲染的字体大小。
          */
         get actualFontSize(): number;
         set actualFontSize(value: number);
         /**
@@ -2612,9 +2612,8 @@
         get _bmFontOriginalSize(): number;
         protected _string: string;
         protected _horizontalAlign: HorizontalTextAlignment;
         protected _verticalAlign: VerticalTextAlignment;
-        protected _actualFontSize: number;
         protected _fontSize: number;
         protected _fontFamily: string;
         protected _lineHeight: number;
         protected _overflow: Overflow;
@@ -2633,9 +2632,9 @@
         protected _enableShadow: boolean;
         protected _shadowColor: math.Color;
         protected _shadowOffset: math.Vec2;
         protected _shadowBlur: number;
-        protected _N$file: Font | null;
+        protected _actualFontSize: number;
         protected _texture: SpriteFrame | __private._cocos_2d_assembler_label_font_utils__LetterRenderTexture | null;
         protected _ttfSpriteFrame: SpriteFrame | null;
         protected _userDefinedFont: Font | null;
         protected _assemblerData: __private._cocos_2d_assembler_label_font_utils__ISharedLabelData | null;