[beats receivers] Return a standard unsupported error type when configuration translation is not yet supported

[cmacknz]

• Relates [beats receivers] Test that translated Elasticsearch exporter configurations work with: self-signed certificates, mTLS, and proxies #45491

For cases in #45491 which are either untested or known to not yet be supported, for example Kerberos authentication with the Elasticsearch output, return a standardized error type that Elastic Agent can use as a signal to fall back to the standard runtime.

The standardized error should be returned from the ToOtelConfig functions.

beats/libbeat/otelbeat/oteltranslate/outputs/elasticsearch/config_otel.go

Line 69 in 87f0e9c

func ToOTelConfig(output *config.C, logger *logp.Logger) (map[string]any, error) {

[elasticmachine]

Pinging @elastic/elastic-agent-data-plane (Team:Elastic-Agent-Data-Plane)