feat: upgrade hls.js to version 1.6.15 and update related imports & refs

[papphelix]

This PR is a fix for streaming m3u8 url video streaming issue which reduces the quality of video and audio after 10sec of play.

Issue: A half dozen learners and partners that many (but not all) videos are slowing down and distorting the audio. Learner Support and Partner Support have been able to reproduce this. It seems to be happening approximately 10 seconds into the impacted videos.

Solution & tested on Stage edx: By upgrading hls.js to 1.6.15 it solves the playback issue.

Impact: All Streaming using m3u8 url.

Screen.Recording.2025-12-08.at.22.09.34-720.mov

[farhan]

Thanks for bumping the HLS version and fixing the issue.
I’ve left a query.

[feanil]

@papphelix has this change been merged into edx-platform master already? For fixes to release branches we required that they're reviewed and merged into master before we backport them to releases. Can you link to the edx-platform PR here so we can make sure that it merges before this merges.

[papphelix]

@papphelix has this change been merged into edx-platform master already? For fixes to release branches we required that they're reviewed and merged into master before we backport them to releases. Can you link to the edx-platform PR here so we can make sure that it merges before this merges.

Raised a new PR #37936
closing this as suggested