Change the way of preloading fonts

[valentinpalkovic]

Closes #21315

What I did

I have changed the way of how fonts were preloaded. Using preloading resulted in a browser warning because the resource was not used after a couple of seconds after the window.load event.

How to test

1. Create a sandbox
2. Open Storybook
3. There shouldn't be a warning saying the Nunito Sans font was preloaded but not used within a few seconds after the window.load event

Checklist

• Make sure your changes are tested (stories and/or unit, integration, or end-to-end tests)
• Make sure to add/update documentation regarding your changes
• If you are deprecating/removing a feature, make sure to update
  MIGRATION.MD

Maintainers

• If this PR should be tested against many or all sandboxes,
  make sure to add the ci:merged or ci:daily GH label to it.
• Make sure this PR contains one of the labels below.

["cleanup", "BREAKING CHANGE", "feature request", "bug", "documentation", "maintenance", "dependencies", "other"]