fix(e2e): detect gateway workload for health port-forward

[krishicks]

Summary

Fixes the e2e Kubernetes test, which is presently failing with:

ERROR: kubectl health port-forward exited before becoming reachable
Error from server (NotFound): statefulsets.apps "openshell" not found

This is because OpenShell is deployed as a Deployment in HA deployments, not a StatefulSet.

Related Issue

Changes

Testing

• mise run pre-commit passes
• Unit tests added/updated
• E2E tests added/updated (if applicable)

Checklist

• Follows Conventional Commits
• Commits are signed off (DCO)
• Architecture docs updated (if applicable)

[github-actions]

Label test:e2e-kubernetes applied for a42d5c9. Open the existing run and click Re-run all jobs to execute with the label set. The run will execute Kubernetes HA E2E after building the required gateway and supervisor images once. This is an optional proof-of-life suite; failures are visible in the workflow run but do not publish a required CI gate status.

[elezar]

This is a focused and sound fix. The e2e harness now discovers whether the chart created a StatefulSet or Deployment before opening the health port-forward, preserving StatefulSet-backed runs while supporting Deployment-backed installations, including HA.

The optional HA job confirms that this part works: it reaches deployment/openshell, establishes the health port-forward, and passes the readyz database check. Its later supervisor session not connected failures are the known cross-replica routing limitation addressed by #1868, so they should not block this PR.

#2256 contained the same patch and has been closed as superseded by this PR. No blocking concerns from me.

[github-actions]

Label test:e2e applied for a42d5c9. Open the existing run and click Re-run all jobs to execute with the label set. The run will execute the standard E2E suite after building the required gateway and supervisor images once. The matching required CI gate status on this PR will flip green automatically once the run finishes.

[elezar]

@krishicks I have removed the test:e2e-kubernetes label as this actually tests HA k8s which is not yet ready.

[krishicks]

@krishicks I have removed the test:e2e-kubernetes label as this actually tests HA k8s which is not yet ready.

Ah, OK. Well, at least it fails now for a better reason than before!