Remove CONSOLE_ADMIN_API_KEY

[christeredvartsen]

We are currently using CONSOLE_ADMIN_API_KEY to set an initial API key for the admin service account. This is used for local development, and will only work on an empty instance of Console.

Instead of using this we can use the CONSOLE_STATIC_SERVICE_ACCOUNTS configuration value to create an initial admin service account using the following JSON:

[
  {
    "name": "nais-local-admin",
    "apiKey": "some key",
    "roles": ["Admin"]
  }
]