Remove `variant` prop from KeybindingHint Chord component

[langermank]

Closes https://github.com/github/primer/issues/6142

Removes the variant prop and replaces it with Tooltip specific CSS. Primary was handled previously.

Depends on https://github.com/github/github-ui/pull/7169 merging to unblock test failures.

Changelog

New

Changed

Removed

Rollout strategy

• [ ] Patch release
• [ ] Minor release
• [x] Major release; if selected, include a written rollout or migration plan
• [ ] None; if selected, include a brief description as to why

Testing & Reviewing

Merge checklist

• [ ] Added/updated tests
• [ ] Added/updated documentation
• [ ] Added/updated previews (Storybook)
• [ ] Changes are SSR compatible
• [ ] Tested in Chrome
• [ ] Tested in Firefox
• [ ] Tested in Safari
• [ ] Tested in Edge
• [ ] (GitHub staff only) Integration tests pass at github/github (Learn more about how to run integration tests)

[changeset-bot[bot]]

🦋 Changeset detected

Latest commit: 9b11466b9cc47aff8f4726b27fd37b40bd29e5b4

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
@primer/react	Major
@primer/mcp	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[github-actions[bot]]

:wave: Hi, this pull request contains changes to the source code that github/github-ui depends on. If you are GitHub staff, test these changes with github/github-ui using the integration workflow. Or, apply the integration-tests: skipped manually label to skip these checks.