fix(runtime-core): hydration should not be performed during the HMR reload process(fix #7706)

[Jevon617]

Close #7706.

During HMR reload, the div element is unmounted. However, in SSR mode, the mountComponent process does not remount the div element but hydrates it instead, causing the issue of the div element is deleted.

[edison1105]

This is not the proper fix. if the initial VNode has el it means it needs hydration. so the proper fix should clear vnode.el before reload.

core/packages/runtime-core/src/apiCreateApp.ts

Lines 383 to 392 in 1bad606

	context.reload = () => {
	// casting to ElementNamespace because TS doesn't guarantee type narrowing
	// over function boundaries
	render(
	cloneVNode(vnode),
	rootContainer,
	namespace as ElementNamespace,
	)
	}
	}

changes to

const cloned = cloneVNode(vnode)
cloned.el = null
render( 
  cloned, 
  rootContainer, 
  namespace as ElementNamespace, 
) 

BTW, this PR requires a test case.