CHORE: bring opsgenie-heart beat image to the mirror

• chore(heartbeat): bring heartbeat image to this repo, build it, and lets maintain it. We can archive the repository once this is merged

Why?

We want to have an updated mirror with images we use and avoid using extra repositories that are not maintained anymore.

Original motivation is because trivy-operator alerted that our alpine image is insecure and we need to update it asap.

What?

Do some little refactoring in the script and after this is finished we can safely archive the repo:

paas-public/opsgenie-heartbeat