38x layout uiTransform cannot vary width and height based on sub objects

[tangkaikk]

Re: # https://github.com/cocos/3d-tasks/issues/19128

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.

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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.

[github-actions]

Code Size Check Report

Wechat (WASM)	Before	After	Diff
2D Empty (legacy pipeline)	1009857 bytes	1009857 bytes	✅ 0 bytes
2D All (legacy pipeline)	2675416 bytes	2675785 bytes	⚠️ +369 bytes
2D All (new pipeline)	2767152 bytes	2767521 bytes	⚠️ +369 bytes
(2D + 3D) All	10024150 bytes	10024519 bytes	⚠️ +369 bytes

Web (WASM + ASMJS)	Before	After	Diff
(2D + 3D) All	16843212 bytes	16843581 bytes	⚠️ +369 bytes

Interface Check Report

! WARNING this pull request has changed these public interfaces:

@@ -56922,8 +56922,9 @@
         protected _layoutDirty: boolean;
         protected _childrenDirty: boolean;
         protected _usefulLayoutObj: UITransform[];
         protected _init: boolean;
+        protected bottomBoundaryOfLayout: number;
         /**
          * @en
          * Perform the layout update.
          *