fix(voice): mark stream as ended

[nyapat]

Please describe the changes this PR makes and why it should be merged:

closes #8778

example:

• subscribe to user.
• user starts speaking (pipeline is: check if subscription exists, if stream exists, voice packets are decrypted, and pushed to stream)
• user stops speaking (specifically when endbehavior aftersilence or afterinactivity determines its 'stopped', push null to mark end)
• user starts speaking (subscription exists: yep, stream exists: yep, push to stream!)
• error: pushing after stream EOF

Status and versioning classification:

• Code changes have been tested against the Discord API, or there are no code changes
• I know how to update typings and have done so, or typings don't need updating

[vercel]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

2 Skipped Deployments

Name	Status	Preview	Comments	Updated (UTC)
discord-js	⬜️ Ignored (Inspect)	Visit Preview		Aug 25, 2024 9:53am
discord-js-guide	⬜️ Ignored (Inspect)	Visit Preview		Aug 25, 2024 9:53am

[vladfrangu]

If possible, can we get a test script for this too? 🙏

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 50.77%. Comparing base (8fb4008) to head (d6a380e).
Report is 52 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #10455   +/-   ##
=======================================
  Coverage   50.77%   50.77%           
=======================================
  Files         228      228           
  Lines       20711    20713    +2     
  Branches     1258     1259    +1     
=======================================
+ Hits        10515    10517    +2     
  Misses      10152    10152           
  Partials       44       44           

Flag	Coverage Δ
voice	63.71% <100.00%> (+0.07%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[nyapat]

drafted because putting tests was a good idea and i found undesirable behaviour (particularly annoying because the tests & actual context of the function don't align properly)

[vladfrangu]

Considering voice is an "if may work" basis, and assuming you've tested this with actual discord behavior, LGTM