COMPLETES #< SPARK-502882 >

This pull request addresses

When a VBG image/video is enabled and the user toggles off the video, only the Camera source gets shut and the effect tends to stay in the Local Stream.

by making the following changes

Fixes the issue mentioned

https://github.com/webex/webex-js-sdk/assets/131742425/e64a69eb-f023-4dfc-8601-f423cb3f3ec5

Change Type

[x] Bug fix (non-breaking change which fixes an issue)
[ ] New feature (non-breaking change which adds functionality)
[ ] Breaking change (fix or feature that would cause existing functionality to change)
[ ] Documentation update
[ ] Tooling change
[ ] Internal code refactor

The following scenarios where tested

< ENUMERATE TESTS PERFORMED, WHETHER MANUAL OR AUTOMATED >

I certified that

[ ] I have read and followed contributing guidelines
[ ] I discussed changes with code owners prior to submitting this pull request
[ ] I have not skipped any automated checks
[ ] All existing and new tests passed
[ ] I have updated the documentation accordingly

Make sure to have followed the contributing guidelines before submitting.

webex / webex-js-sdk