chore(deps): bump formidable and artillery in /src/load-generator (#519)

Removes [formidable](https://github.com/node-formidable/formidable). It's no longer used after updating ancestor dependency [artillery](https://github.com/artilleryio/artillery). These dependencies need to be updated together.


Removes `formidable`

Updates `artillery` from 2.0.0-34 to 2.0.10
- [Release notes](https://github.com/artilleryio/artillery/releases)
- [Commits](artilleryio/artillery@v2.0.0-34...artillery-2.0.10)

---
updated-dependencies:
- dependency-name: formidable
  dependency-type: indirect
- dependency-name: artillery
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>