Exclude unnecessarily tracked coverage files

[kpowkitty]

Closes #30525

What I did

Glob excluded certain files that test coverage was unnecessarily including, which was causing coverage to incorrectly report dramatically lower than its true results.

Checklist for Contributors

Testing

The changes in this PR are covered in the following automated tests:

• stories
• unit tests
• integration tests
• end-to-end tests

Manual testing

Before changes:

1. Run yarn start
2. Open Storybook in your browser
3. Open the test component module
4. Turn on 'coverage' in its settings menu
5. Run tests -> Notice poor coverage rate

After changes:

1. Run yarn start
2. Open Storybook in your browser
3. Open the test component module
4. Turn on 'coverage' in its settings menu
5. Run tests -> Notice 100% coverage rate

Documentation

• Add or update documentation reflecting your changes
• If you are deprecating/removing a feature, make sure to update
  MIGRATION.MD

Checklist for Maintainers

• When this PR is ready for testing, make sure to add ci:normal, ci:merged or ci:daily GH label to it to run a specific set of sandboxes. The particular set of sandboxes can be found in code/lib/cli-storybook/src/sandbox-templates.ts

• Make sure this PR contains one of the labels below:

  Available labels

  • bug: Internal changes that fixes incorrect behavior.
  • maintenance: User-facing maintenance tasks.
  • dependencies: Upgrading (sometimes downgrading) dependencies.
  • build: Internal-facing build tooling & test updates. Will not show up in release changelog.
  • cleanup: Minor cleanup style change. Will not show up in release changelog.
  • documentation: Documentation only changes. Will not show up in release changelog.
  • feature request: Introducing a new feature.
  • BREAKING CHANGE: Changes that break compatibility in some way with current major version.
  • other: Changes that don't fit in the above categories.

🦋 Canary release

This PR does not have a canary release associated. You can request a canary release of this pull request by mentioning the @storybookjs/core team here.

core team members can create a canary release here or locally with gh workflow run --repo storybookjs/storybook canary-release-pr.yml --field pr=<PR_NUMBER>

Greptile Summary

Based on the provided information, I'll create a concise summary of the pull request:

Updates test coverage configuration to exclude non-source files from coverage calculations, providing more accurate coverage metrics in Storybook Test addon.

• Added coverage exclusions in code/addons/test/src/node/vitest-manager.ts for .storybook, story files, and build artifacts
• Fixes issue [Bug]: Storybook code coverage should ignore storybook-static #30525 where storybook-static was incorrectly included in coverage
• Prevents artificially low coverage numbers caused by including configuration and build files
• Improves accuracy of test coverage reporting in the Storybook UI test module
• Maintains existing test coverage functionality while filtering out irrelevant files

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[greptile-apps]

LGTM

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