[MM-219] Fix issue of username not visible in jitsi embed meeting

[ayusht2810]

Summary

• Fixed issue of username not visible in jitsi embed meeting
• Updated the display name in jitsi window meeting from full name to username
• Fixed and updated test cases

Ticket Link

NA

Screenshot

What to test?

• Check if the username is present in the jitsi meeting window.

[Kshitij-Katiyar]

@mickmister Gentle reminder to review the PR