docs: remove blog.johnnyreilly.com Google Analytics tag from docs part 2

[johnnyreilly]

Pre-flight checklist

• I have read the Contributing Guidelines on pull requests.
• If this is a code change: I have written unit tests and/or added dogfooding pages to fully verify the new behavior.
• If this is a new API or substantial change: the PR has an accompanying issue (closes #0000) and the maintainers have approved on my working plan.

Motivation

Fixing up my mistaken committing of my gtag id to the Docusaurus repo. A follow on from #8313

Gosh my stats / SEO are such a mess now.

Test Plan

Test links

Deploy preview: https://deploy-preview-_____--docusaurus-2.netlify.app/

Related issues/PRs

[netlify]

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[github-actions]

⚡️ Lighthouse report for the deploy preview of this PR

URL	Performance	Accessibility	Best Practices	SEO	PWA	Report
/	🟢 90	🟢 97	🟢 100	🟢 100	🟢 90	Report
/docs/installation	🟠 71	🟢 100	🟢 100	🟢 100	🟢 90	Report

[johnnyreilly]

Thanks!