fix(@dpc-sdp/ripple-ui-core): vertical nav indentation

[lambry]

Issue: https://digital-vic.atlassian.net/browse/SD-1774

What I did

• Update vertical nav indents, some menu items show as 'sub/indented' items even when they aren't

How to test

Reference menu: https://develop.content-vic.sdp.delivery/admin/structure/menu/manage/site-main-menu-vicgovau-protect
Current: https://develop.vic-gov-au.sdp.delivery/develop-school-child-safety-and-wellbeing-policy
Updated: https://app.pr-1383.vic-gov-au.sdp4.sdp.vic.gov.au/develop-school-child-safety-and-wellbeing-policy

Checklist

For all PR's

• I've added relevant changes to the project Readme if needed
• I've updated the documentation site as needed
• I have added tests to cover my changes (if not applicable, please state why in a comment)

For new UI components only

• I have added a storybook story covering all variants
• I have checked a11y tab in storybook passes
• I have added cypress component tests (if the component is interactive)
• Any events are emitted on the event bus using emitRplEvent