Inspect topics_allowed to extend the list of allowed topics
Double compute streams might want to set a "preferred" topic by default but still allow client to resume consumption from a replicated topic in case a switchover happens.
Setting a stream configuration like:
my-stream.v1:
topics:
- eqiad.my-stream.v1
topics_allowed:
- eqiad.my-stream.v1
- codfw.my-stream.v1
should allow achieving this goal. KafkaSSE already supports separating the topics to consume (when no Last-Event-ID is prevent) from the list of allowed topics so we should use this capability.
Bug: T382065