Support Multi-Zone Managed Instance Group in GCP
## Problem to solve Currently the plugin cannot use Multiple zones Managed Instance Group (MIG) in GCP. When I try to use MIG with Multiple zones enabled, I get an error: ``` failed to update executor: initializing taskscaler: creating taskscaler: initializing provisioner: reconciling with instance group: rpc error: code = Unknown desc = googleapi: Error 404: The resource 'projects/test-gitlab-runners/zones/europe-north1/instanceGroupManagers/test-gitlab-runners-instance-group' was not found, notFound executor=docker-autoscaler max_builds=1 runner=t2_xxx ``` When I try to use the Single zone MIG, it works fine. ## Implementation proposal - {placeholder}
issue