test(styleguide): skip tests on full icon, illustration, pattern galleries

[aresnik11]

Skip render/a11y tests on the full asset gallery stories

The icon/illustration/pattern "gallery" stories each render every asset in the set and then run axe over all of them. Under @storybook/addon-vitest that's slow and low-value — each catalog is redundant with its component's Default story. This excludes just the galleries from the test run while keeping them browsable in Storybook.

What changed

Added tags: ['!test'] to the gallery stories:

• Icons/Mini → AllMiniIcons
• Icons/Regular → RegularInterfaceIcons, RegularLearningEnvironmentIcons, RegularVendorIcons, RegularSkillIcons
• Illustrations → AllIllustrations
• Patterns → AllPatterns

How it works

Storybook auto-applies a test tag to every story, and addon-vitest runs the tagged ones. tags: ['!test'] removes that tag from a single story, so the test run ignores it — a per-story opt-out. The stories still render normally in yarn start:storybook; only the automated render + a11y check is skipped. Each component's Default (representative) story still runs, so the component itself stays covered.

Effect on the run

Test count per file drops to just Default:

• Mini 2 → 1, Regular 5 → 1, Illustrations 2 → 1, Patterns 2 → 1

That removes the slowest, most-redundant stories from the Vitest sweep.

Testing instructions

# 1. Each gallery file should now report a single test (Default only)
yarn test:stories Mini Regular Illustrations Patterns
#    → expect "1 test" per file; the All* / gallery stories are not executed

Also confirm they're still visible in the UI: yarn start:storybook → the gallery stories (AllMiniIcons, AllIllustrations, AllPatterns, the Regular icon galleries) still render in the sidebar and canvas; they're just absent from the test run.

PR Checklist

• Related to designs:
• Related to JIRA ticket: GMT-1793
• Version plan added/updated (or not needed)
• I have run this code to verify it works
• This PR includes unit tests for the code change
• This PR includes testing instructions tests for the code change
• The alpha package of this PR is passing end-to-end tests in all relevant Codecademy repositories