[FEATURE] CI proves custom sizing survives upgrades #3694

On kind, install the previous release with custom sizing, upgrade to the current release, and assert operator choices survive.

Tracks "Prove it in CI" in the Operator Supplied Values workstream of the Extensible Install Roadmap.

Current state (0b635b80): the upgrade e2e test (#2712) has no sizing checks.

Required changes. Extend the upgrade e2e test, or add a job, that asserts:

• custom values survive the upgrade;
• an autoscaler-owned replica count survives a hand-off ([FEATURE] ate-setup release-field hands a field to another owner #3690) and a redeploy;
• the drift report ([FEATURE] ate-setup reports out-of-band changes before overwriting them #3689) catches a kubectl scale.

Render tests: default output equals today's values, and --cluster-size=size10 equals today's large profile.

Dependencies: #3168, #3688, #3689, #3690.

Parent Issue: #3165