C210K: Polish scaletest infrastructure

[f0ssel]

There is some polish needed on the infrastructure side to make this safe and ready to be ran regularly:

• Use cert-manager to allow us to use https coder endpoints
• Use otel-collector to push traces to GCP
• Push prometheus data to C210K: Long-term Prometheus data storage #150 once setup
• Use random password for first user
• Add capability to "start" at a given number to exp scaletest create-workspaces