[WIP] - Remove Twitter account linking documentation

[kartykp]

Twitter account linking functionality has been completely removed from both the UI and backend, so this PR updates the documentation to reflect these changes.

Changes made:

• Removed the entire "Linking your npm and Twitter accounts" section from managing profile settings
• Removed "Removing your Twitter account from npm" section
• Updated the account settings list to remove "Link Twitter Account"
• Updated 2FA configuration docs to remove Twitter as a linked account option for account recovery
• Updated privacy policy to remove references to Twitter data collection
• Updated requesting data documentation to remove Twitter account from the list of personal details
• Removed Twitter connect functionality from shared.js
• Updated 4 screenshots to reflect the current UI without Twitter linking

Files modified:

• content/getting-started/managing-your-npm-user-account/managing-your-profile-settings.mdx
• content/getting-started/managing-your-npm-user-account/requesting-your-data.mdx
• content/getting-started/setting-up-your-npm-user-account/configuring-two-factor-authentication.mdx
• content/policies/privacy.mdx
• src/shared.js
• 4 screenshot images in static/getting-started/

Manual testing:

• Verify the documentation pages render correctly without any broken links or references to Twitter
• Check that the GitHub account linking section still displays properly on the account settings page
• Confirm that the 2FA recovery options documentation is clear and accurate
• Review the privacy policy page to ensure it reads naturally without Twitter mentions
• Test the "Requesting your data" page to verify the list of personal details is complete

Test results:

No automated tests were added as this is a documentation-only change. The existing linting and formatting checks pass successfully.