[EPIC] Operator Controlled Install Settings #3165

Tracks the Operator Supplied Values workstream of the Extensible Install Roadmap.

Goal

Operators set replicas, CPU, memory, and disruption budgets for every component through the install's own inputs: a kustomize patch, a Helm value, or an ate-setup Component. They can also hand a field to another owner, such as a HorizontalPodAutoscaler. Those choices survive every redeploy and every upgrade step. An out-of-band change is reported before the install overwrites it.

General Requirements

• Move replicas, resources, and disruption budgets out of the base manifests into a default sizing Component. Replace the large-cluster profile with a second sizing Component (ate-setup does not allow customizing the resource configurations of Substrate components #2579; contract [FEATURE] Add Sizing Contract for --component based sizing (kustomize) #3168; PR ate-setup deploy accepts --component, and control plane sizing moves into kustomize Components #3179).
• Keep caller-supplied Components in ate-setup's install record, and merge partial deploys into the record instead of replacing it ([FEATURE] ate-setup install record merges partial deploys and stores Components #3688).
• Report fields another owner changed before ate-setup overwrites them. The first release only reports ([FEATURE] ate-setup reports out-of-band changes before overwriting them #3689).
• Add a command that hands a field to another owner, such as an autoscaler, without resetting it ([FEATURE] ate-setup release-field hands a field to another owner #3690).
• Refuse changes to Postgres storage size or class that the cluster cannot apply ([FEATURE] Refuse Postgres storage size or class changes the cluster cannot apply #3691).
• Helm sizing values, where null leaves the field to another owner ([FEATURE] Helm sizing values #3692).
• Rewrite the upgrade runbook for every install path ([DOCS] Upgrade runbook for every install path #3693), and add CI proving sizing survives an upgrade ([FEATURE] CI proves custom sizing survives upgrades #3694).

Parent Issue: #3158