refactor(infra): get rid of nested stacks

[guilhem-fry]

IaC Setup Overhaul in Pulumi

Context

The PR addresses issues in our existing Infrastructure as Code (IaC) setup using Pulumi. Previously, our setup involved multiple stacks for each environment (dev, staging, and production) and branch, leading to confusion and challenges in resource management. This also resulted in IAM inconsistencies across stacks.

Solution

This PR eliminates the concept of environment stacks, consolidating infrastructure management into a single stack per environment. It involves significant changes, including:

• Removal of redundant stacks.
• Integration of developer environments, replacing PR environments.
• Deletion of setup_env.py and integration of its IaC content into deploy_service.py, which is now renamed to deploy.py.
• Additional configuration tweaks.

Developer Environments

New Stack Management Approach

Stack	Environment
production	Production
staging	Staging
staging--	Staging
development	Development
development--<developer's name>	Development

Key Points

• Each developer or project maintainer will manage their own testing stack, named development--<developer's name>.
• This approach reduces the number of stacks in the Cloud, lowering costs and simplifying tracking.

Notes

• Approximately a dozen outdated stacks have been deleted to streamline the setup.

[guilhem-fry]

This is a major improvement, thanks.

Something to bear in mind for the documentation is that I found the relationship between the production environment and the production stack to be a bit confusing. In various places, the code checks that the name of the stack is "production" but doesn't check the name of the environment. It would help to know what things are governed by the environment vs the stack.

All good to merge, though.

Thanks Duncan, I'll keep this in mind