Use metrics to display runner statuses instead of status field for EphemeralRunnerSet and AutoscalingRunnerSet

[nikola-jokic]

There is no need for updating the status at points to display information about ephemeral runner state aggregations. Metrics are way more useful place to do it. Therefore, we should move this information to a metric.

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[Copilot]

Pull request overview

This PR moves ephemeral runner lifecycle aggregation visibility from status fields on EphemeralRunnerSet / AutoscalingRunnerSet into Prometheus metrics, and introduces a shared lifecycle bucketing helper to keep the aggregation deterministic.

Changes:

• Add Prometheus gauges for additional EphemeralRunner lifecycle buckets (succeeded/outdated/deleting) and a new SetEphemeralRunnerCountsByLifecycle setter API.
• Remove runner-count fields from EphemeralRunnerSetStatus / AutoscalingRunnerSetStatus (types + CRDs) and update controllers/tests to stop relying on those status fields.
• Introduce AggregateEphemeralRunnerLifecycle to consistently bucket EphemeralRunners (with deletion timestamp precedence) and update controller logic to use it.

Reviewed changes

Copilot reviewed 18 out of 18 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
controllers/actions.github.com/metrics/metrics.go	Adds new lifecycle gauges and replaces the old 3-bucket setter with a 6-bucket lifecycle setter.
controllers/actions.github.com/metrics/metrics_test.go	Adds unit tests for the new metrics setter and CommonLabels contract.
controllers/actions.github.com/metrics/lifecycle_metrics_integration_test.go	Adds an integration-style test that gathers metrics from the controller-runtime registry.
controllers/actions.github.com/ephemeralrunnerset_controller.go	Stops publishing ephemeral runner count metrics from the ERS reconciler and simplifies ERS status to Phase only.
controllers/actions.github.com/ephemeralrunnerset_controller_test.go	Updates tests to assert runner counts by listing EphemeralRunner objects instead of using ERS status fields.
controllers/actions.github.com/ephemeralrunner_lifecycle.go	Adds a shared lifecycle bucketing helper with deletion-timestamp precedence.
controllers/actions.github.com/ephemeralrunner_lifecycle_test.go	Adds thorough unit tests for lifecycle bucketing precedence and totals.
controllers/actions.github.com/ephemeralrunner_controller.go	Emits lifecycle metrics on runner lifecycle/status changes and adds a PublishMetrics gate to the reconciler.
controllers/actions.github.com/autoscalingrunnerset_controller.go	Replaces “active runners” check based on ERS status fields with a list+aggregate of EphemeralRunners.
controllers/actions.github.com/autoscalingrunnerset_controller_test.go	Updates tests to stop asserting autoscaling status runner-count fields.
config/crd/bases/actions.github.com_ephemeralrunnersets.yaml	Removes ERS status count fields/printcolumns from the CRD schema.
config/crd/bases/actions.github.com_autoscalingrunnersets.yaml	Removes ARS status count fields/printcolumns from the CRD schema.
charts/gha-runner-scale-set-controller/crds/actions.github.com_ephemeralrunnersets.yaml	Mirrors the ERS CRD schema changes in the Helm chart CRDs.
charts/gha-runner-scale-set-controller/crds/actions.github.com_autoscalingrunnersets.yaml	Mirrors the ARS CRD schema changes in the Helm chart CRDs.
charts/gha-runner-scale-set-controller-experimental/crds/actions.github.com_ephemeralrunnersets.yaml	Mirrors the ERS CRD schema changes in the experimental chart CRDs.
charts/gha-runner-scale-set-controller-experimental/crds/actions.github.com_autoscalingrunnersets.yaml	Mirrors the ARS CRD schema changes in the experimental chart CRDs.
apis/actions.github.com/v1alpha1/ephemeralrunnerset_types.go	Removes ERS status count fields and associated kubebuilder printcolumns.
apis/actions.github.com/v1alpha1/autoscalingrunnerset_types.go	Removes ARS status count fields and associated kubebuilder printcolumns.

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