Fix broken snippet__line outside of snippet_block--numbered

[ClementChaumel]

Done

Fix snippet__line displaying incorrectly when used outside of snippet_block--numbered

Fixes #4357

QA

• Open demo
• It should display correctly
• inspect the page and take --numbered out of the parent element's class
• it shouldn't display any numbers

Check if PR is ready for release

If this PR contains Vanilla SCSS code changes, it should contain the following changes to make sure it's ready for the release:

• PR should have one of the following labels to automatically categorise it in release notes:
  • Feature 🎁, Breaking Change 💣, Bug 🐛, Documentation 📝, Maintenance 🔨.
• Vanilla version in package.json should be updated relative to the most recent release, following semver convention:
  • if CSS class names are not changed it can be bugfix relesase (x.x.X)
  • if CSS class names are changed/added/removed it should be minor version (x.X.0)
  • see the wiki for more details
• Any changes to component class names (new patterns, variants, removed or added features) should be listed on the what's new page.
• Documentation side navigation should be updated with the relevant labels.

Screenshots

Current behaviour:

After this is merged:

[webteam-app]

Demo starting at https://vanilla-framework-4363.demos.haus/docs/examples/patterns/code-snippet/numbered

[bethcollins92]

LGTM! First Vanilla PR in the bag 🥳