Update Dialog large heading size

[langermank]

Part of https://github.com/github/primer/issues/4257
Closes https://github.com/github/primer/issues/5952

Basically removing the large variant but just visually so this isn't a proper major..

[changeset-bot]

🦋 Changeset detected

Latest commit: afa5797

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

This PR includes changesets to release 1 package

Name	Type
@primer/view-components	Minor

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[Copilot]

Pull Request Overview

This PR updates the Dialog component to make the large heading size the same as the default size, effectively removing the visual distinction of the large variant while maintaining API compatibility.

Key changes:

• Standardized dialog title font sizes to use small title shorthand across different dialog variants
• Improved CSS selector formatting for better readability
• Added explanatory comment about the non-breaking nature of this change

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[Copilot]

CSS property syntax values should use double quotes instead of single quotes for consistency with the CSS specification and better tooling support.

Suggested change

	syntax: '<length>';
	syntax: "<length>";

[github-actions]

⚠️ Visual or ARIA snapshot differences found

Our visual and ARIA snapshot tests found UI differences. Please review the differences by viewing the files changed tab to ensure that the changes were intentional.

Review differences

[jonrohan]

🤘🏻