fix: fastQualitySwitch stability

[adrums86]

Description

Currently, our fastQualitySwitch triggers a full video/main buffer clear twice. This is because we clear the buffer first with a resetEverything call on the mainSegmentLoader, then once that removal is complete we call setCurrentTime which calls resetEverything on all active segment loaders, clearing all the other buffers as well. This is causing some instability, specifically when a quality change occurs at or near a discontinuity.

Specific Changes proposed

Instead of calling setCurrentTime after a fastQualitySwitch, lets just call load on the mainSegmentLoader.
Note: There were 2 browser bugs that seemed to require a setCurrentTime call according to the comments, but after checking both URLs, those bugs seem to no longer be relevant, so we should be safe removing this part and only calling load.

Requirements Checklist

• Feature implemented / Bug fixed
• If necessary, more likely in a feature request than a bug fix
  • Unit Tests updated or fixed
  • Docs/guides updated
  • Example created (starter template on JSBin)
• Reviewed by Two Core Contributors

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.31%. Comparing base (0b4da7c) to head (8ecccc5).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1525   +/-   ##
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  Coverage   86.31%   86.31%           
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  Files          43       43           
  Lines       11097    11097           
  Branches     2532     2532           
=======================================
  Hits         9578     9578           
  Misses       1519     1519           

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[dzianis-dashkevich]

Do we want to load other loaders here?

[adrums86]

I don't think it's necessary, the only reason load was previously called on all the loaders was due to setCurrentTime calling pause then resetEverything on all the loaders, including the mainSegmentLoader a second time.

http-streaming/src/playlist-controller.js

Line 1535 in 0b4da7c

this.mainSegmentLoader_.pause();