Duplicate class on related links social example

[rmccar]

Because of how the logic works in the related links and list components the example with the social links and icons(https://service-manual.ons.gov.uk/design-system/components/related-content/example-related-content-social-media) has the ons-list--bare class added twice.

The logic needs updating so it is only added once but this will have implications on other lists that don't use the social icons because this logic is also used by them so there may be some refactoring needed, this will have to be taken into considerations when fixing this bug.