Garden-prometheus should scrape aggregate-prometheus instances

[wyb1]

What would you like to be added:

Garden-prometheus should scrape aggregate-prometheus instances.

TODOs:

• New scrape config
• Monitoring should be deployed after seeds
• The ingress domain of each seed needs to be read and inserted into the scrape config with the prefeix p-seed. It should look like this: p-seed.ingress.domain.from.seed

Why is this needed:

Improved observability and a way to aggregate data from all seeds.