fix: remove orphaned submodule registration for benchmark app (#164)

<!-- CURSOR_SUMMARY -->
> [!NOTE]
> **Low Risk**
> Low risk: removes an orphaned git submodule registration and does not
change application runtime behavior.
> 
> **Overview**
> Removes an orphaned git submodule registration for the benchmark app
to clean up repository configuration and avoid broken submodule
references.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
720988c. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: mario-launchdarkly