chore: removing unused fonts folder and files from design-tokens

[georgewrmarshall]

Description

As part of the design tokens migration, this pull request removes the unused fonts folder and files from the merged-packages/design-tokens directory. These fonts were previously used for Storybook, but they are now duplicated and unnecessary because the storybook-react application (apps/storybook-react/fonts) provides the required fonts.

Related

• https://github.com/MetaMask/metamask-design-system/pull/128

Manual Testing Steps

1. Ensure fonts/ folder and files have been removed from merged-packages/design-tokens
2. Ensure there are no references to merge-packages/design-tokens/docs/fonts folder or files in the codebase

Screenshots

Ensuring merge-packages/design-tokens/docs/fonts folder is not referenced in the codebase

Pre-merge Author Checklist

• [x] Followed MetaMask Contributor Docs.
• [x] Ensured all PR status checks passed at least once.
• [x] Updated relevant CHANGELOG files.
• [x] Applied appropriate labels and linked issues.

Pre-merge Reviewer Checklist

• [ ] Verified manual tests for the build and migration.
• [ ] Reviewed CHANGELOG entries and downstream dependency updates.
• [ ] Checked for unresolved TODOs in the codebase.