Media: Fix broken video muting

[swissspidy]

Context

It seems like video muting got broken because the new file name (of the muted version) we sent to WP did not include the extension, so WP blocks it.

We haven't changed that code in a long time, so maybe this got broken because of a change on the WP side.

Summary

This change ensures that the newly muted video file name includes the file extension.

Relevant Technical Choices

To-do

User-facing changes

No visual changes

Testing Instructions

• This is a non-user-facing change and requires no QA

This PR can be tested by following these steps:

1. Insert a video from the library or record one
2. Try to remove audio via the style panel
3. Verify that removing audio works.

Reviews

Does this PR have a security-related impact?

Does this PR change what data or activity we track or use?

Does this PR have a legal-related impact?

Checklist

• This PR addresses an existing issue and I have linked this PR to it in ZenHub
• I have tested this code to the best of my abilities
• I have verified accessibility to the best of my abilities (docs)
• I have verified i18n and l10n (translation, right-to-left layout) to the best of my abilities
• This code is covered by automated tests (unit, integration, and/or e2e) to verify it works as intended (docs)
• I have added documentation where necessary
• I have added a matching Type: XYZ label to the PR

---

Fixes #12040

[googleforcreators-bot]

Plugin builds for 3c8881d are ready 🛎️!

• Download development build
• Download production build