Add instance runner with AWS plugin to runners.gitlab-ci.yml
We need to create a runner configuration in the https://gitlab.com/gitlab-org/ci-cd/tests/runner-incept test project configured to use the AWS plugin from the official repository. And we need to add an entry to the hello-world tests to use it.
The purpose of this to verify integration of the entire runner / taskscaler / fleeting / plugin pipeline. It will be a bare minimum test and only for one cloud provider. Other tests will verify the runner / taskscaler integration. And the fleet / plugin integrations, one per plugin.
Edited by Joe Burnett