fix(runtime-core): recursive querying of fragments when find singleRoot

[yangxiuxiu1115]

fix #10087 ,It seems like there is a lack of test cases, which makes me think and think

[github-actions]

Size Report

Bundles

File	Size	Gzip	Brotli
runtime-dom.global.prod.js	89.8 kB (+61 B)	34.2 kB (+45 B)	30.8 kB (+16 B)
vue.global.prod.js	147 kB (+61 B)	53.4 kB (+19 B)	47.8 kB (+30 B)

Usages

Name	Size	Gzip	Brotli
createApp	50.1 kB	19.6 kB	18 kB
createSSRApp	53.4 kB	20.9 kB	19.1 kB
defineCustomElement	52.4 kB	20.4 kB	18.6 kB
overall	63.9 kB (+61 B)	24.7 kB (+30 B)	22.4 kB (-6 B)

[yyx990803]

Thanks for the PR, but there's already #8593 with test cases (just haven't got to merge it)