fix(compiler-ssr): resolve tag name from _attrs in transition group

[edison1105]

close #12827

[github-actions]

Size Report

Bundles

File	Size	Gzip	Brotli
runtime-dom.global.prod.js	100 kB	38 kB	34.3 kB
vue.global.prod.js	158 kB	57.8 kB	51.5 kB

Usages

Name	Size	Gzip	Brotli
createApp (CAPI only)	46.4 kB	18.2 kB	16.6 kB
createApp	54.3 kB	21.2 kB	19.3 kB
createSSRApp	58.5 kB	22.9 kB	20.9 kB
defineCustomElement	59.2 kB	22.8 kB	20.7 kB
overall	68.4 kB	26.3 kB	24 kB

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@vue/compiler-core

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@vue/compiler-sfc

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@vue/runtime-core

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@vue/runtime-dom

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@vue/shared

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vue

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@vue/compat

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commit: 92bf78e