Initialize scroller with correct height on SSR

### Clear and concise description of the problem

When using SSR, the scroll container does not have the correct height for the number of elements applied until hydration.

### Suggested solution

the scroll divs should have the correct height for the given number of items rather than only containing the pre-rendered elements then expanding on hydration

### Alternative

_No response_

### Additional context

_No response_

### Validations

- [x] Read the [docs](https://github.com/Akryum/vue-virtual-scroller/blob/master/packages/vue-virtual-scroller/README.md).
- [x] Check that there isn't [already an issue](https://github.com/Akryum/vue-virtual-scroller/issues) that reports the same bug to avoid creating a duplicate.