fix(codeapi-chart): support sandbox runner scale to zero

[rschlaefli]

What This Fixes

This PR lets the service-worker start when codeapi-sandbox-runner is owned by an external autoscaler.

The chart already has workerSandbox.sandboxRunner.externalAutoscaler=true for KEDA-style ownership. With this PR, that existing setting also skips the service-worker init container that waits for a live sandbox runner. Default installs are unchanged.

Branch Coverage

• Base: main
• Head: 607e019
• Reviewed: 1 commit, 1 file changed, 2 insertions.
• Covered: conditional rendering of wait-for-sandbox-runner based on existing workerSandbox.sandboxRunner.externalAutoscaler.

Verification

Current head:

• helm template codeapi helm/codeapi -n codeapi --set executionManifest.privateKey=dummy --set executionManifest.publicKey=dummy --show-only templates/worker-sandbox-deployment.yaml | rg "name: wait-for-" -> renders wait-for-redis and wait-for-sandbox-runner.
• helm template codeapi helm/codeapi -n codeapi --set executionManifest.privateKey=dummy --set executionManifest.publicKey=dummy --set workerSandbox.sandboxRunner.externalAutoscaler=true --show-only templates/worker-sandbox-deployment.yaml | rg "name: wait-for-" -> renders wait-for-redis only.
• git diff --check uzh/main...HEAD -> pass.

GitHub Actions:

• API Unit Tests on 607e019 -> running after force-push.
• Service Unit Tests on 607e019 -> running after force-push.

Earlier branch verification:

• The previous head passed both GitHub Actions jobs before the simplification; current head is smaller and rerunning.

Security / Privacy

• Review: chart-only deployment behavior change.
• Result: no new images, secrets, RBAC, permissions, network paths, or runtime code.
• Sensitive data: no secret values included.

Blocking Before Merge

• GitHub Actions pass on 607e019.
• Reviewer accepts using existing workerSandbox.sandboxRunner.externalAutoscaler as the scale-to-zero signal.

Follow-Up After Merge

• Update df-cloud CodeAPI target revision to the merged commit.
• Merge the helm-charts companion change that adds BullMQ active KEDA triggers.

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