Use FreeBSD autoscaler for "stress" tests
The FreeBSD autoscaler has been configured to utilize the new "instance" GitLab Runner executor to spawn "stress" test CI jobs on AWS EC2 dynamically. A shared GitLab Runner named "freebsd-instance-autoscaler" has been set up in GitLab CI/CD to communicate with EC2, provisioning VM instances on demand based on a FreeBSD 13 AMI image. This image is the same as the one previously used for FreeBSD "stress" tests before the implementation of autoscaling (specifically, the "freebsd13-amd64-bind9stress.aws.lab.isc.org" GitLab Runner in CI/CD).
Validation pipeline: https://gitlab.isc.org/isc-projects/bind9/-/pipelines/173169