fix(`@vtmn/svelte`, `@vtmn/css`): fix timeout on overlays components

[Tlahey]

Changes description

Today the timeout inside the VtmnAlert / VtmnSnackbar / VtmnToast are broken.

Thanks to this fix, it is possible to apply a timeout from 1ms to Infinity on those components without breaking changes !

Fix also an issue with a large text

Context

On NFS it is not possible to apply an alert more than 8s.

Checklist

• [x] Make sure you are requesting to pull a topic/feature/bugfix branch. Please, don't request directly from your main!
• [x] Check commits & PR names matches our requested structure. It must follow the https://www.conventionalcommits.org pattern.
• [x] Check your code additions will fail neither code linting checks.
• [x] I have reviewed the submitted code.
• [x] I have tested on related showcases.
• [x] If it includes design changes, please ask for a review design-system-core-team-design GitHub team.

Does this introduce a breaking change?

• No

Other information