Tolerate actuator endpoints with the same id in the configuration processor

[mhalbritter]

#32046 adds a reactive session endpoint with the same id as the servlet one. Our spring-boot-configuration-processor then emits multiple properties for the group, for the enabled and for the cache TTL property. This in turn trips up our asciidoctor extension.

We should fix the spring-boot-configuration-processor to tolerate endpoints with the same id. However, it should fail if the enableByDefault value from the @Endpoint annotation differs between the endpoints with the same id.