Fix undefined reference error when uninstalling extensions

[msujew]

What it does

Closes #10828

The previous code referenced the global variable location, which was undefined. The new code references the loop variable.

How to test

1. Install an extension and uninstall it directly after that
2. The UI should refresh
3. The backend should have logged a message about the uninstalled location

Review checklist

• As an author, I have thoroughly tested my changes and carefully followed the review guidelines

Reminder for reviewers

• As a reviewer, I agree to behave in accordance with the review guidelines

[cdamus]

Thanks, @msujew! Best to keep the code simpler, after all.

[vince-fugnitto]

I confirm that the changes work well 👍

• undeploying extensions (ex: vsx-registry view) works well.
• the logs regarding undeployment work well, and the approach is simpler.