Configurable time to display Session time remaining. Or at least set to 6mins.

Describe the bug When a session has a set duration, a banner appears on the top showing the remaining time. However, that countdown banner appear super early, 30 mins before. For a session with 30 mins duration, the banner is visible the entire time, which is undesired.

To Reproduce Steps to reproduce the behavior:

1. Use API mate to create a session with duration=30
2. Join that session

Expected behavior No banner at first, the banner shows X minutes before the end (X configurable in config file)

Actual behavior Hardcoded 30 minutes before the session ends the timer is anchored at the top. https://github.com/bigbluebutton/bigbluebutton/blame/v3.0.x-release/bbb-graphql-server/bbb_schema.sql#L2500

Screenshots

BBB version: BigBlueButton 3.0.34