Add gitlab runners to monitoring

User Story

As a Infra-dev,
I want our gitlab-runners are monitored,
So that I know when there are problems with runners or servers

Scope

• Provisioning of Alloy / Node-Exporter
• Scrapping the runners
• Creation of alerts if needed

ACs

Given I provision a VM as gitlab-runner with ansible,
When I check the running containers,
Then I see node exporter and alloy running

Given I provision a VM as gitlab-runner with ansible,
When I check prometheus,
Then I see node and gitlab-runner metrics

Given I provision a VM as gitlab-runner with ansible,
When I open the node-exporter dashboard in grafana,
Then I will see node metrics of my gitlab runner instances