fix(KeepAlive): avoid cache suspense comment root

[edison1105]

close #6028

[edison1105]

/ecosystem-ci run

[github-actions]

Size Report

Bundles

File	Size	Gzip	Brotli
runtime-dom.global.prod.js	90.1 kB (+35 B)	34.5 kB (+10 B)	31.1 kB (-23 B)
vue.global.prod.js	147 kB (+35 B)	54 kB (+8 B)	48 kB (-2 B)

Usages

Name	Size	Gzip	Brotli
createApp	49.6 kB	19.5 kB	17.8 kB
createSSRApp	53.2 kB	20.9 kB	19.1 kB
defineCustomElement	51.9 kB	20.2 kB	18.5 kB
overall	63.2 kB (+35 B)	24.5 kB (+9 B)	22.3 kB (+51 B)

[vue-bot]

📝 Ran ecosystem CI: Open

suite	result	latest scheduled
language-tools	❌ failure	❌ failure
nuxt	❌ failure	❌ failure
pinia	✅ success	✅ success
primevue	✅ success	✅ success
quasar	✅ success	✅ success
radix-vue	✅ success	✅ success
router	✅ success	✅ success
test-utils	✅ success	✅ success
vant	✅ success	✅ success
vite-plugin-vue	✅ success	✅ success
vitepress	✅ success	✅ success
vue-i18n	✅ success	✅ success
vue-macros	✅ success	❌ failure
vuetify	✅ success	✅ success
vueuse	✅ success	✅ success
vue-simple-compiler	✅ success	✅ success