Elastic APM migration : provide list of config options without migration path

Some of the configuration options of Elastic APM Java agent already have a clear migration path to their equivalents with EDOT described in [Migration](https://www.elastic.co/docs/reference/opentelemetry/edot-sdks/java/migration) documentation.

However, most of them do not have an equivalent in OpenTelemetry/EDOT because:
- related feature is not available with EDOT/OpenTelemetry
- configuration option is tied to classic APM agent implementation, and even if there is an equivalent feature the feature implementation does not provide a similar configuration option

For a user migrating from Elastic APM Java agent to EDOT Java, we usually recommend to review the current configuration and create the equivalent EDOT configuration from it.

However it could be confusing for users as they currently have to infer from the absence of any reference in the Migration documentation that the configuration option does not have an equivalent. The goal is is to make that explicit.

Implementing this task would likely require to:
- enumerate all the public configuration options of Elastic APM Java agent
- add an explicit list in Migration documentation with all those unsupported configuration options