Error Tracking Metrics

[ev-shindin]

Add a counter to track errors by component, replacing the need to parse logs for error rates.

Metrics:

wva_errors_total                    counter {component, error_type}

Implementation:

• Components: collector, analyzer, optimizer, limiter, enforcer, controller
• Increment on every logger.Error() call in engine and controller
• Consider a helper metrics.RecordError(component, errorType string) to keep call sites clean

Acceptance Criteria:

• Error counter emitted for each component
• At least one error path per component has metric increment
• Unit tests verify counter increments on error paths

[shuynh2017]

@ev-shindin, qq: just to make sure, what would be the error_type, is it just msg string in logger.Error ? e.g.;

logger.Error(err, "Failed to find VA for deployment event using index",
			"deployment", deploy.Name,
			"namespace", deploy.Namespace)
logger.Error(err, "Unable to fetch VariantAutoscaling",
			"name", req.Name,
			"namespace", req.Namespace)
logger.Error(err, "Failed to get scale target "+va.Spec.ScaleTargetRef.Kind,
			"name", scaleTargetName,
			"namespace", va.Namespace)