Remove Unused extractHtmlMeta Function and Related Test Cases

[nnabeyang]

• Deleted extractHtmlMeta: Removed the extractHtmlMeta function, which became unused after the changes introduced in PR Use proxy for fetching link meta #716 .
• Test Cleanup: Deleted corresponding test files and mock data from the following files:
  • exampleComHtml.ts
  • tiktokHtml.ts
  • youtubeChannelHtml.ts
  • youtubeHtml.ts
  • extractHtmlMeta.test.ts
• Updated link-meta logic: Cleaned up references in html.ts, twitter.ts, and youtube.ts to reflect the removal of the unused function, ensuring no unnecessary code remains.