Latest available product version is duplicated inside the showfor picker if the user's version exceeds the selectable options

[emilghittasv]

Steps to reproduce
Steps to reproduce the behavior:

1. Using Firefox 137.0 navigate to the https://support.allizom.org/en-US/kb/Certificate-contains-the-same-serial-number-as-another-certificate kb article.
2. Click on the version picker from the Customize this article section.

Expected behavior
The Version 121 (latest available version in stage) is selected since 137.0 exceeds the latest available version in stage and no UI issues are displayed.

Actual behavior
The Version 121 is successfully selected but the 121 version is duplicated inside the showfor dropdown menu.

Screenshots

Desktop:

• OS: Windows 11
• Browser: Firefox

Additional context
This issue is reproducible in stage.

[akatsoulas]

PR mozilla/kitsune#6614

[emilghittasv]

I can confirm that this issue is verified fixed in stage.

I'm moving this ticket inside the release column.