fix(legacy): custom attribute that set format error

[troublemaker52025]

Re: #

Changelog

• 错误地引用上一个 attr 指针替换为正确的 ca.attr.format, 并删除了残留的错误注释
• createMesh可能存在typo导致带custom attribute的mesh计算错误 cocos-engine#19071

与之前 bug 的本质区别：

	标准属性模块(position/normal/uv...)	旧版(customAttributes 块)
进入前attr重置	√ attr = nullptr	× 无重置，沿用上一块的值
attr赋值来源	当前属性从(geometry.attributes 或 defAttrs[N])	错误地仍指向上一个标准属性
info是否正确	√	×

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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.

[troublemaker52025]

@cocos-robot run test cases

[github-actions]

Code Size Check Report

Wechat (WASM)	Before	After	Diff
2D Empty (legacy pipeline)	1014446 bytes	1014446 bytes	✅ 0 bytes
2D All (legacy pipeline)	2681971 bytes	2681971 bytes	✅ 0 bytes
2D All (new pipeline)	2773763 bytes	2773763 bytes	✅ 0 bytes
(2D + 3D) All	10031072 bytes	10031072 bytes	✅ 0 bytes

Web (WASM + ASMJS)	Before	After	Diff
(2D + 3D) All	16867485 bytes	16867485 bytes	✅ 0 bytes

Interface Check Report

This pull request does not change any public interfaces !

[github-actions]

@troublemaker52025, Please check the result of run test cases:

• Test Platform: PR-Test
• Editor Version: v4.0.0
• Task Result: FAIL
• Task URL: https://cctest.cocos.org/#/reportview/PR-TEST/6160411f-6358-46c5-ad5b-4603c5180e85/-1
• GitHub Action: https://github.com/cocos/cocos4/actions/runs/29562831712

Task Details

Platform	build	boot	runned	crashScene	FailScene
web-mobile	PASS	PASS	FAIL		graphics-draw-before-init
ios	PASS	PASS	PASS
mac	PASS	PASS	PASS

[github-actions]

@troublemaker52025, Please check the result of run test cases:

• Test Platform: PR-Test
• Editor Version: v4.0.0
• Task Result: PASS
• Task URL: https://cctest.cocos.org/#/reportview/PR-TEST/e6c12c8a-ab9a-4dad-8cf3-4a805039486b/-1
• GitHub Action: https://github.com/cocos/cocos4/actions/runs/29562831712

Task Details

[github-actions]

@troublemaker52025, Please check the result of run test cases:

• Test Platform: PR-Test
• Editor Version: v4.0.0
• Task Result: PASS
• Task URL: https://cctest.cocos.org/#/reportview/PR-TEST/6182b191-e8ee-406b-bcb0-4a9fd6c80c8d/-1
• GitHub Action: https://github.com/cocos/cocos4/actions/runs/29563133716

Task Details

[github-actions]

@troublemaker52025, Please check the result of run test cases:

• Test Platform: PR-Test
• Editor Version: v4.0.0
• Task Result: PASS
• Task URL: https://cctest.cocos.org/#/reportview/PR-TEST/4b49f709-6d49-4c4b-b31d-27614862341a/-1
• GitHub Action: https://github.com/cocos/cocos4/actions/runs/29563133716

Task Details

[github-actions]

@troublemaker52025 ❗ There was an error during the execution of the tasks. Please check the logs for more details.