Switch deprecated OTel component aliases to snake_case names

[Copilot]

OpenTelemetry Collector renamed several components to a snake_case convention, keeping the previous names as deprecated aliases. This switches the generated Collector configuration to the new names.

Renames were verified against OTel collector/contrib v0.152.x, matching the default axoflow collector image (axoflowOtelCollectorImageRef in collector_manager.go). Only four components used by this project have been renamed:

Deprecated alias	New name	Kind
k8sattributes	k8s_attributes	processor
filelog	file_log	receiver
otlphttp	otlp_http	exporter
otlp	otlp_grpc	exporter

Components not yet renamed at the target version (deltatocumulative, awss3, elasticsearch, basicauth, bearertokenauth, count, routing, prometheus, …) are left unchanged.

Changes

• Config generation — GetExporterNameForOutput now emits otlp_grpc/ and otlp_http/ exporter names; generateProcessors and pipeline.go emit k8s_attributes and file_log/.
• Validator — updated the bare-component exception map key to k8s_attributes.
• Tests & fixtures — updated exporter unit tests and the golden complex.yaml, preserving output-name substrings (e.g. otlp-test-output).
• Docs/comments — updated the demo generated-config example, README, and code comments referencing the old names.

// pkg/resources/otel_conf_gen/pipeline/components/common.go
case output.Spec.OTLPGRPC != nil:
    exporterName = fmt.Sprintf("otlp_grpc/%s_%s", output.Namespace, output.Name)
case output.Spec.OTLPHTTP != nil:
    exporterName = fmt.Sprintf("otlp_http/%s_%s", output.Namespace, output.Name)

Note: OTLPGRPC/OTLPHTTP CRD field names and their JSON tags are unchanged — only the emitted Collector component type names are affected.

[csatib02]

Folded into #216 as the 'breaking changes' commit.