Create Load Test Scenarios on GitHub Actions

Establish a strategy to have the load tests created and executed from GitHub Actions. K6 already provides recommendations on how to create the GitHub Actions (https://k6.io/blog/load-testing-using-github-actions/) so we need to adapt it to our scenario and create the needed structure.

- [ ] Review and follow the instructions as per K6 documentation: https://k6.io/blog/load-testing-using-github-actions
- [ ] Set some thresholds to indicate success or failure.
- [ ] Allow env variables to be read from GitHub (secrets) and consumed by the load test scenarios.
- [ ] Create at least one fully functional scenario from the existing ones to set the structure to be followed.
- [ ] Add github action to deploy `load-test-gateway` to DEV/TEST