feat(wrt): strip temporal_ prefix from HPA metric matchLabels when en…

[pranavthakur0-0]

Fixes #588

What was changed

• Added default-off controller flag --wrt-hpa-match-labels-strip-temporal-prefix and env WRT_HPA_MATCH_LABELS_STRIP_TEMPORAL_PREFIX.
• Added Helm value workerResourceTemplate.hpaMatchLabelsStripTemporalPrefix (schema + manager Deployment env).
• When enabled, auto-injected WorkerResourceTemplate HPA external metric matchLabels use worker_deployment_name, worker_build_id, and namespace instead of temporal_worker_deployment_name, temporal_worker_build_id, and temporal_namespace.
• Plumbed the setting through reconciler → planner → WRT renderer; webhook rejects the unprefixed keys when stripping is enabled (same controller-owned guarantee as temporal_*).
• Documented the Helm setting in docs/worker-resource-templates.md.
• Unit tests (env parsing, render/planner, webhook) and Helm validate workflow checks for the new env default and --set true.

Why?

Self-hosted Temporal Server OpenMetrics use native label names (worker_deployment_name, etc.). Temporal Cloud metrics use the temporal_* prefix. Today the controller always injects temporal_*, which breaks HPA external metrics against self-hosted backends unless operators rename labels out of band. This implements the maintainer plan for #588: optional prefix stripping on the three hardcoded injected keys only, without changing KEDA triggers, pod selectors, or metric values.

Testing

• go test ./api/v1alpha1 ./internal/k8s ./internal/planner ./internal/controller
• Helm validate CI / helm template asserts WRT_HPA_MATCH_LABELS_STRIP_TEMPORAL_PREFIX defaults to false and renders true when the value is enabled

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