🔍 fix: USE_REDIS condition, Markdown list counter, code highlights

[danny-avila]

Summary

Closes #3804

• Updated the USE_REDIS condition check in clearPendingReq.js and socialLogins.js to use the isEnabled utility function, ensuring consistent evaluation of the USE_REDIS environment variable.
• Restored the Markdown rehype highlight functionality in Markdown.tsx, MessageContent.tsx, and Part.tsx components, which was being accidentally removed programmatically in a previous update
• Removed the isEdited prop from Markdown component as it's no longer needed for controlling the rehype plugins.
• Simplified the Markdown component usage in MessageContent and Part components by removing the unnecessary isEdited prop.
• Fixed markdown list counter as a regression from recent changes to list styling