fix(markdown): mdx-code-block should support intentation

[slorber]

Motivation

Fix #10220

Test Plan

Unit tests

[netlify]

✅ [V2]

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[github-actions]

⚡️ Lighthouse report for the deploy preview of this PR

URL	Performance	Accessibility	Best Practices	SEO	PWA	Report
/	🟠 63	🟢 98	🟢 96	🟢 100	🟠 88	Report
/docs/installation	🟠 67	🟢 96	🟢 100	🟢 100	🟠 88	Report
/docs/category/getting-started	🟠 76	🟢 100	🟢 100	🟢 90	🟠 88	Report
/blog	🟠 70	🟢 100	🟢 100	🟢 90	🟠 88	Report
/blog/preparing-your-site-for-docusaurus-v3	🟠 64	🟢 96	🟢 100	🟢 100	🟠 88	Report
/blog/tags/release	🟠 70	🟢 100	🟢 100	🟢 90	🟠 88	Report
/blog/tags	🟠 76	🟢 100	🟢 100	🟢 90	🟠 88	Report

[github-actions]

Size Change: 0 B

Total Size: 1.84 MB

ℹ️ View Unchanged

Filename	Size
website/.docusaurus/codeTranslations.json	2 B
website/.docusaurus/docusaurus.config.mjs	27.1 kB
website/.docusaurus/globalData.json	123 kB
website/.docusaurus/i18n.json	930 B
website/.docusaurus/registry.js	304 kB
website/.docusaurus/routes.js	202 kB
website/.docusaurus/routesChunkNames.json	130 kB
website/.docusaurus/site-metadata.json	2.17 kB
website/build/assets/css/styles.********.css	112 kB
website/build/assets/js/main.********.js	897 kB
website/build/index.html	38.1 kB

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