The LokiStack CRD allows for customizing the handling of OTLP attributes passed in during ingestion of OTel log entries. This is documented here: https://loki-operator.dev/docs/open-telemetry.md/#custom-attribute-mapping

Currently the CRD allows configuring "stream labels" and "structured metadata" but has no configuration for dropping (ignoring) attributes, even though the Loki configuration allows this.

We should extend the CRD to allow customers to drop attributes by name or regular expression and make it clear that "structured metadata" is the default for all attributes if no configuration is provided. If possible, the current "structured metadata" configuration might be deprecated or removed because it just provides the default behavior.

Note: As this is a backport into a past release, this change needs to be backwards-compatible with the current API provided by 6.1, so the implementation will need to be slightly different from the implementation in 6.2