Bump dependencies: k8s.io v0.35, prometheus v0.311.3, otel v1.42, Go 1.26.3

[mitali-salvi]

Summary

Bumps major dependencies to latest compatible versions:

Dependency	From	To
k8s.io/*	v0.33.1	v0.35.4
sigs.k8s.io/controller-runtime	v0.21.0	v0.23.3
github.com/prometheus/prometheus	v0.48.1	v0.311.3
go.opentelemetry.io/otel	v1.39.0	v1.42.0
golang.org/x/crypto	v0.46.0	v0.52.0
golang.org/x/net	v0.48.0	v0.55.0
github.com/docker/docker	v25.0.13	v28.5.2
Go runtime	1.25.9	1.26.3

Code Changes

• target-allocator: Adapted to prometheus-operator v0.91 API changes (StoreBuilder, slog logger, simplified GenerateServerConfiguration)
• featuregate: Updated gate IDs to comply with new alphanumeric-only validation, migrated to RegisterFlags API
• webhooks: Migrated to controller-runtime v0.23 typed webhook API (Validator[T], Defaulter[T])
• podmonitor: Port field changed from string to *string
• prehook/relabel: Migrated to labels.NewBuilder and relabel.ProcessBuilder

Testing

• go build ./... passes
• 20 test packages pass
• Remaining test failures are pre-existing (missing kubebuilder envtest binaries, port conflicts, integration test needing k8s cluster)

[mitali-salvi]

In controller-runtime v0.23, the webhook interfaces changed from untyped to generic:

  - Old: admission.CustomValidator — methods receive runtime.Object, you manually cast and check
  - New: admission.Validator[*AmazonCloudWatchAgent] — methods receive *AmazonCloudWatchAgent directly

The type safety that was enforced at runtime with if !ok { return fmt.Errorf(...) } is now enforced at compile time by the generic type parameter.