Fix duplicate messgaes in history after re-connecting (v2)

[sushmi21]

This PR prevents duplicate messages in chat history by not prepending messages to the message history on re-connect.

Success Criteria:

• Reconnecting behaviour should remain unaffected. Reconnect screen should appear, chat history should not disappear
• In chat history, redunant messages should not appear on re-connecting
• please do a thorough testing to avoid regression

How to test:

• Send a message to the bot and wait for a response.
• Now, in browser console, select network to 'Offline' or simply disconnect your PC's wifi
• After few minutes, put your network to 'No throttling' or connect the wifi back.
• Check SC

[sushmi21]

I have added a comment and just commented the line of code instead of removing it, for future reference.

[Dujma]

This also fixes this ticket? #335

So I can close it.