fix(content-docs): make getActivePlugin match plugin paths more exactly

[Josh-Cena]

Motivation

Fix #6434

Have you read the Contributing Guidelines on pull requests?

Yes

Test Plan

Added two tests

[netlify]

✔️ [V2]

🔨 Explore the source changes: e4aeeb3

🔍 Inspect the deploy log: https://app.netlify.com/sites/docusaurus-2/deploys/61eb96447c1c450008086bfd

😎 Browse the preview: https://deploy-preview-6435--docusaurus-2.netlify.app

[github-actions]

⚡️ Lighthouse report for the changes in this PR:

Category	Score
🟠 Performance	75
🟢 Accessibility	100
🟢 Best practices	93
🟢 SEO	100
🟢 PWA	92

Lighthouse ran on https://deploy-preview-6435--docusaurus-2.netlify.app/

[github-actions]

Size Change: +49 B (0%)

Total Size: 708 kB

Filename	Size	Change
website/build/assets/js/main.********.js	531 kB	+49 B (0%)

ℹ️ View Unchanged

Filename	Size
website/.docusaurus/globalData.json	43.5 kB
website/build/assets/css/styles.********.css	104 kB
website/build/index.html	29.6 kB

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