Essential Contacts

[aumohr]

Describe the bug
The current templates do not create a value for Essential Contacts which is recommend by GCP security best practices.

Rational
Many Google Cloud services, such as Cloud Billing, send out notifications to share important information with Google Cloud users. By default, these notifications are sent to members with certain identity and access management (IAM) roles. With Essential Contacts, you can customize who receives notifications by providing your own list of contacts.

Recommendation
We recommend adding groups as contacts, then managing the membership of those groups to determine who receives notifications. This practice helps ensure that notifications always go to active employees.

Expected behavior
Use groups from Bootstrap stage for Essential Contacts.