v2.72.rc1

• SUP-14895 - Second Classroom recording stuck in buffering on mobile
• SUP-15427 - Black thumbnails in chapters.
• FEC-8515 - V2 - HLS.js - non critical error stop playback
• FEC-8538 - Playback restarts after midroll on iOS
• FEC-8534 - rename HLS.js level switch events (#3908)